Microbial clean-up of uranium in the presence of molybdenum using pretreated Acidithiobacillus ferrooxidans

Bioremediation of uranium (Ⅵ) using a native strain Halomonas campaniensis ZFSY-04 isolated from uranium mining and milling effluent: Potential and mechanism

A significant surge in the exploitation of uranium resources has resulted in considerable amounts of radioactive effluents. Thus, efficient and eco-friendly uranium removal strategies need to be explored to ensure ecological safety and resource recovery. In this study, we investigated the resistance of Halomonas campaniensis strain ZFSY-04, isolated from an evaporation pool at a uranium mine site, and its potential mechanism of uranium (Ⅵ) removal. The results showed that the strain exhibited unique uranium tolerance and its growth was not significantly inhibited under a uranium concentration of 700 mg/L. It had a maximum loading capacity of 865.40 mg/g (dry weight), achieved following incubation under uranium concentration of 100 mg/L, pH 6.0, and temperature 30 °C, for 2 h, indicating that the removal of uranium by the strain was efficient and rapid. Combined with kinetic, isothermal, thermodynamic, and microspectral analyses, the mechanism of uranium loading by strain ZFSY-04 was metabolism-dependent and diverse, including, physical and chemical adsorption on the cell surface, extracellular biomineralisation, intracellular bioaccumulation, and biomineralisation. Our results highlight the unique properties of indigenous strains, including high resistance, high efficiency, rapid uranium removal, and various uranium removal strategies, which make it suitable as a new tool for in situ bioremediation and uranium-contaminated environmental resource recovery.

A Biotechnological Strategy for Molybdenum Extraction Using Acidithiobacillus ferrooxidans

Biosorption is a potential tool for the extraction of metals from contaminated water and recovery of precious metals, which is a convenient alternative to conventional processes. In the present study, molybdenum recovery by Acidithiobacillus ferrooxidans strain ZT-94 was evaluated. Additionally, the effects of pH initial concentration of molybdenum, contact time, adsorbent concentration, and temperature on the biosorption were investigated. As revealed by the results, the greatest amount of molybdenum sorption was achieved at pH 5. By increasing the concentration of molybdenum from 2 to 45 mg/l, the molybdenum removal increases from 71.13 to 150 mg/g dry weight of biomass, but biosorption efficiency decreased. Also, increasing the dry weight of biomass from 0.008 to 0.06 g/l degreased the biosorption efficiency from 20.68 to 85.69%. The results of molybdenum biosorption were evaluated by Langmuir and Freundlich adsorption isotherm. The maximum biosorption capacity for molybdenum extraction was 150.497 mg/g and amount which is very suitable for a biosorbent. The biosorption was examined by scanning electron microscopy-energy-dispersive X-ray spectroscopy. Because of the elevated biosorption properties of molybdenum by this biosorbent, it can be concluded that Acidithiobacillus ferrooxidans strain ZT-94 is a promising candidate for the removal and recovery of molybdenum from aqueous systems.