Release of Phosphorus to Promote Biomineralization of Uranium by Saccharomyces Cerevisiae Based on Spectroscopy Analysis

Phosphorus, as one of the necessary chemical elements for organisms, plays an important role in the process of uranium mineralization by microorganisms. The adsorption characteristics of U (VI) on Saccharomyces cerevisiae were investigated in this study. The relationship among the pH value of the adsorption solution, the concentration of U(VI) and phosphorus released in the process of biosorption were investigated by ICP-OES and ICP-MS. The mechanism of biomineralization of uranium by S. cerevisiae is speculated combined with spectroscopy and mesoscopic analysis. The results show that S. cerevisiae could effectively remove U(VI) from wastewater, and the phosphorus released by cells in the biosorption effectively promotes the biomineralization of uranium. The removal efficiency of U(VI) by S. cerevisiae is best at the initial solution pH is 3. 0. The H+ in solution and phosphorus released by cells were involved in the removal of U(VI) by S. cerevisiae. The adsorption process was independent of temperature. Combined with FTIR, SEM, XPS and XRD analysis, it is speculated that the mechanism of biomineralization of uranium by S. cerevisiae as follows ; firstly, U(VI) was rapidly adsorbed on the cell surface of S. cerevisiae by electrostatic attraction, then it was complex with phosphorus groups, hydroxyl groups, amide and other functional groups on the cell surface. Hydrogen ions in the solution and inorganic phosphorus released by S. cerevisiae could be combined with uranium as precipitation ligands, and continue to mineralize to form crystal on the extracellular surface of the cell. During this process, a part of hexavalent uranium was reduced to tetravalent uranium and then settled. In conclusion, phosphorus is the main functional element that caused the biomineralization of uranium by S. cerevisiae. It is of great significance to study the biomineralization mechanism of uranium in which phosphorus is involved in the bioremediation of uranium pollution and to understand the activation and immobilization ofuranium in nature.