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

This study explored the feasibility of calcium peroxide (CaO₂) to inhibit cyanobacterial blooms of the outbreak and dormancy stages. Our previous studies have found that CaO₂ has a high inhibitory effect on cyanobacteria. In order to explore the application effect of CaO₂ in actual cyanobacteria lake water, we conducted this study to clarify the effect of CaO₂ on inhibiting cyanobacteria in outbreak and dormancy stages. The results showed that CaO₂ 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, CaO₂ 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 CaO₂ on the downregulation of photosynthesis-related genes (rbcL and psaB), microcystn (mcyA and mcyD) and peroxiredoxin (prx), and verified the mechanism of CaO₂ 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.