Mechanic Analysis Of Uranium Adsorption In Staphylococcus Aureus LZ-01

Staphylococcus aureus LZ-01was isolated from Lanzhou reach of the Yellow River which was able to resist and reduce Cr(Ⅵ) to Cr(Ⅲ).Microbial strains can efficiently reduce Cr(Ⅵ) under both anaerobic and aerobic conditions. We carefully reviewed molecular mechanism of microbial Cr(Ⅵ) reduction in this paper. Microbes reduce Cr(Ⅵ) mainly through3pathways. ChrR, nitroreductase and some flavin proteins are efficient Cr(Ⅵ) reductases. NAD(P)H is their electron donor. Thioredoxin binding protein in Desulfovibrio alaskensis G20can reduce U(Ⅵ) and Cr(Ⅵ), glutaredoxin acts as the electron donor. Cytochrome C from sulfate-and iron-reducing strains can also efficiently reduce U(Ⅵ) and Cr(Ⅵ). More and more Cr(Ⅵ) reduction strains and Cr(Ⅵ) reduction pathways in microbial strains have been reported. The mechanism of microbial Cr(Ⅵ) reduction has become more and more clear. Microbial Cr(Ⅵ) reduction was thought to be a best way of chromium remediation.Some studies have shown that hexavalent uranium and chromium have similar chemical properties and ionic structure. Microbial strains resist and reduce U(Ⅵ) with the same Cr(Ⅵ) resistance and reduction pathways. But current studies have shown that microbial U(Ⅵ) reduction can not be achieved under aerobic condition. Microbial adsorption of U(Ⅵ) was thought to be a potential method to remediation uranium contamination. In this study, we investigated strain LZ-01’s Uranium (Ⅵ) resistance and adsorption ability. Our results showed that it can resist2mmolL-1U(Ⅵ) and adsorb96%of2mmol·L-1U(Ⅵ) after6hours incubation. Transmission Electron Microscopy (TEM) images showed that uranium precipitates were formed on the surface of the cells. Energy Dispersive X-Ray Spectroscopy (EDX) analysis indicated that the precipitates were consisted of uranium and phosphorus. Uranium adsorption rate of strain LZ-01was promoted by20mmol·L-1phosphate. It adsorbed45%in2.5mmol·L-1U(Ⅵ) in30minutes comparing to36%without phosphate (P<0.05). Strain LZ-01can resist many kinds of heavy metals and acidic condition. It may survive under nuclear waste environment. Strain LZ-01might be a potential bioremediation strain for nuclear waste.