Effect of different phosphate sources on uranium biomineralization by the Microbacterium sp. Be9 strain: A multidisciplinary approach study

Abstract

IntroductionIndustrial activities related with the uranium industry are known to generate hazardous waste which must be managed adequately. Amongst the remediation activities available, eco-friendly strategies based on microbial activity have been investigated in depth in the last decades and biomineralization-based methods, mediated by microbial enzymes (e.g., phosphatase), have been proposed as a promising approach. However, the presence of different forms of phosphates in these environments plays a complicated role which must be thoroughly unraveled to optimize results when applying this remediation process.MethodsIn this study, we have looked at the effect of different phosphate sources on the uranium (U) biomineralization process mediated by Microbacterium sp. Be9, a bacterial strain previously isolated from U mill tailings. We applied a multidisciplinary approach (cell surface characterization, phosphatase activity, inorganic phosphate release, cell viability, microscopy, etc.).Results and DiscussionIt was clear that the U removal ability and related U interaction mechanisms by the strain depend on the type of phosphate substrate. In the absence of exogenous phosphate substrate, the cells interact with U through U phosphate biomineralization with a 98% removal of U within the first 48 h. However, the U solubilization process was the main U interaction mechanism of the cells in the presence of inorganic phosphate, demonstrating the phosphate solubilizing potential of the strain. These findings show the biotechnological use of this strain in the bioremediation of U as a function of phosphate substrate: U biomineralization (in a phosphate free system) and indirectly through the solubilization of orthophosphate from phosphate (P) containing waste products needed for U precipitation.

Impact of microbial processes on the safety of deep geological repositories for radioactive waste

“…Such modifications can lead to changes in the oxidation state of some radionuclides, affecting their solubility and mobility through the repositories. However, microorganisms can directly influence the mobility of radionuclides and other elements through different processes such as intracellular accumulation, biotransformation (redox reactions) biosorption, or biomineralization ( Shukla et al, 2017 ; Lopez-Fernandez et al, 2020 ; Ruiz-Fresneda et al, 2020a ; Martinez-Rodriguez et al, 2022 ; Figure 4 ).…”

“…These results confirm the capacity of these bacteria to biomineralize uranium, which had been enhanced by the G2P amendment through phosphatase activity. In the study of Martinez-Rodriguez et al (2022) Microbacterium sp. Be9 strain was used, previously isolated from U-mill tailings and determined that the U-biomineralization process was dependent on the type of phosphate source.…”

“…Be9 strain was used, previously isolated from U-mill tailings and determined that the U-biomineralization process was dependent on the type of phosphate source. This is relevant for the bioremediation of uranium since the solubilization of orthophosphates derived from waste products containing P-compounds could occur ( Martinez-Rodriguez et al, 2022 ). However, high concentrations of uranium could produce a harmful effect on bacterial activity.…”

New Techniques and Applications of Bioprocess inspired Manufacturing and Synthesis

“…Moreover, it has been discovered that the naturally generated protein polymers Bombyx mori silk fibroin may guide the regulated mineralization of diverse nanomaterials because of its distinctive self-assembly behavior, high cytocompatibility, and biomechanical capabilities. In order to create more efficient lithium (Li-ion) cells, Martínez-Rodríguez et al [15] used a biomineralization approach based on the effective framework of silk proteins to create hierarchical olive-like organized magnetite and carbon nanomaterials. Cai and Larese-Casanova [16] also showed that they could use this method to make electrocatalyst for high-performance Li-ion batteries.…”