Response mechanism of sediment endogenous phosphorus release to functional microorganisms and its cyanobacterial growth and disappearance effects

Endogenous phosphorus (P) release from lake sediments is an important factor in the eutrophication of overlying waters, as P is the limiting nutrient salt affecting cyanobacterial growth. Microorganisms are also key to the evolution of cyanobacterial growth and disappearance, as they can influence the release of endogenous P. Meanwhile, endogenous phosphorus can also have an impact on microbial structure. However, there is a lack of studies on the response mechanisms between endogenous P release and microorganisms, as well as the exploration of endogenous P release on the whole cyanobacterial growth and disappearance evolution process. In this study, metagenome sequencing was used to characterize the microbial community structure at different times and to explain the P cycle from the perspective of functional genes. The results showed that the number of sediment microorganisms (genes) gradually increased with the P release capacity, and the outbreak with the strongest P release capacity possessed the most abundant microorganisms (genes). Proteobacteria with P solubilizing functions were consistently the most abundant phylum in all four periods and were positively correlated with P release potential assessment factors EPC0, EPC0F, and NAP. Functional genes affect the P cycle by acting primarily on inorganic P solubilization, organic P mineralization, and P transport. These P-functional genes are mainly found in Proteobacteria, Acidobacteria, Chloroflexi, and Actinobacteria microorganisms. In addition, the P form in the sediments was dominated by IP, with the highest concentration (704.86 mg/kg) occurring during the dormant period. Sediments from this period acted as a strong P “sink”, creating a precondition for cyanobacterial recovery and outbreaks to provide a source of P. The results of this study can provide a theoretical basis for controlling endogenous P release at the microscopic level of cyanobacterial growth and disappearance.