title: Different biosorption mechanisms of Uranium(VI) by live and heat-killed Saccharomyces cerevisiae under environmentally relevant conditions.
abstract: Uranium adsorption mechanisms of live and heat-killed Saccharomyces cerevisiae in different pH values and biomass concentrations were studied under environmentally relevant conditions. Compared with live cells, the adsorption capacity of heat-killed cells is almost one order of magnitude higher in low biomass concentration and highly acidic pH conditions. To explore the mesoscopic surface interactions between uranium and cells, the characteristic of uranium deposition was investigated by SEM-EDX, XPS and FTIR. Biosorption process of live cells was considered to be metabolism-dependent. Under stimulation by uranyl ions, live cells could gradually release phosphorus and reduce uranium from U(VI) to U(IV) to alleviate uranium toxicity. The uranyl-phosphate complexes were formed in scale-like shapes on cell surface. The metabolic detoxification mechanisms such as reduction and "self-protection" are of significance to the migration of radionuclides. In the metabolism-independent biosorption process of heat-killed cells: the cells cytomembrane was damaged by autoclaving which led to the free diffusion of phosphorous from intracellular, and the rough surface and nano-holes indicated that the dead cells provided larger contact area to precipitate U(VI) as spherical nano-particles. The high biosorption capacity of heat-killed cells makes it become a suitable biological adsorbent for uranium removal.
authors.affiliation: School of Nuclear Science and Technology, Lanzhou University, NO.222, Tianshui South Road, Chengguan District, Lanzhou 730000, China.
authors.forename: Tieshan
authors.initials: T
authors.lastname: Wang
authors.affiliation: School of Nuclear Science and Technology, Lanzhou University, NO.222, Tianshui South Road, Chengguan District, Lanzhou 730000, China. Electronic address: zhengxy15@lzu.edu.cn.
authors.forename: Xinyan
authors.initials: X
authors.lastname: Zheng
authors.affiliation: School of Nuclear Science and Technology, Lanzhou University, NO.222, Tianshui South Road, Chengguan District, Lanzhou 730000, China.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Wang
authors.affiliation: School of Nuclear Science and Technology, Lanzhou University, NO.222, Tianshui South Road, Chengguan District, Lanzhou 730000, China.
authors.forename: Xia
authors.initials: X
authors.lastname: Lu
authors.affiliation: School of Nuclear Science and Technology, Lanzhou University, NO.222, Tianshui South Road, Chengguan District, Lanzhou 730000, China.
authors.forename: Yanghao
authors.initials: Y
authors.lastname: Shen
mesh_terms: D000327:Adsorption; D011848:Radioactive Pollutants / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D014501:Uranium / Q000378:metabolism*
chemical_list: D011848:Radioactive Pollutants; D014501:Uranium
keywords: Bioremediation; Biosorption capacity; Detoxification mechanisms; Saccharomyces cerevisiae; Uranium waste treatment