Cyanobacterial blooms control with CaO2 in different stages: Inhibition efficiency, water quality optimization and microbial community changes.

This study explored the feasibility of calcium peroxide (CaO 2) to inhibit cyanobacterial blooms of the outbreak and dormancy stages. Our previous studies have found that CaO 2 has a high inhibitory effect on cyanobacteria. In order to explore the application effect of CaO 2 in actual cyanobacteria lake water, we conducted this study to clarify the effect of CaO 2 on inhibiting cyanobacteria in outbreak and dormancy stages. The results showed that CaO 2 inhibited the growth of cyanobacteria in the outbreak and dormancy stages by 98.7% and 97.6%, respectively. The main inhibitory mechanism is: (1) destroy the cell structure and make the cells undergo programmed cell death by stimulating the oxidation balance of cyanobacteria cells; (2) EPS released by cyanobacteria resist stimulation and combine calcium to form colonies, and accelerate cell settlement. In addition to causing direct damage to cyanobacteria, CaO 2 can also improve water quality and sediment microbial diversity, and reduce the release of sediment to phosphorus, so as to further contribute to cyanobacterial inhibition. Finally, the results of qRT-PCR analysis confirmed the promoting effect of CaO 2 on the downregulation of photosynthesis-related genes (rbcL and psaB), microcystn (mcyA and mcyD) and peroxiredoxin (prx), and verified the mechanism of CaO 2 inhibition of cyanobacteria. In conclusion, this study provides new findings for the future suppression of cyanobacterial bloom, by combining water quality, cyanobacterial inhibition mechanisms, and sediment microbial diversity. [Display omitted] • CaO 2 inhibited the growth of cyanobacteria during outbreak and dormancy stages. • CaO 2 inhibited cyanobacteria through oxidative stimulation and colony formation. • 100 mg L−1 CaO 2 enhanced microbial diversity. • Providing the practical application effect of treating cyanobacteria with CaO 2. [ABSTRACT FROM AUTHOR]