Improvement of uranium adsorption in Kocuria rosea by phosphate: A combined physiological and proteomic analysis

Abstract

In this study, a combined physiological and proteomic analysis was performed to investigate the effect of phosphate addition on uranium adsorption response of Kocuria rosea. When 0.4–5 g/L KH₂PO₄ was added to the culture medium, there was no significant change in biomass compared with the control (without KH₂PO₄ addition). Subsequently, the cells were collected and interacted with uranium solution (300 mg/L, 20 mL), and the adsorption rate of uranium was significantly increased from 22.14 % to 65.32 % with 3.0 g/L KH₂PO₄ addition. Meanwhile, the cells could release more phosphorus-containing substances and form thin film like uranium precipitates on the cell surface by fourier transform infrared spectroscopy and scanning electron microscopy characterization analyses. Furthermore, a proteomic approach was employed to reveal the regulation mechanism of phosphate on uranium interaction in the K. rosea cells. The bioinformatics analysis revealed that the differentially abundant proteins in K. rosea were mainly involved in cell motility, ribosomes, structural molecule activity, flagellar assembly, and energy metabolism under uranium stress. Interestingly, up-regulated proteins were significantly enriched for organic acid biosynthetic process in the cells with KH₂PO₄ addition. In addition, KH₂PO₄ led to upregulation of proteins including phosphohydrolase, asparagine synthase, and the phosphotransferase system (PTS) transporter subunit EIIC, which related to phosphate metabolism for regulation of uranium mineralization.