Comparative analysis of uranium bioassociation with halophilic bacteria and archaea

Abstract

Rock salt represents a potential host rock formation for the final disposal of radioactive waste. The interactions between indigenous microorganisms and radionuclides, e.g. uranium, need to be investigated to better predict the influence of microorganisms on the safety assessment of the repository. Hence, the association process of uranium with two microorganisms isolated from rock salt was comparatively studied. Brachybacterium sp. G1, which was isolated from the German salt dome Gorleben, and Halobacterium noricense DSM15987T, were selected as examples of a moderately halophilic bacterium and an extremely halophilic archaeon, respectively. The microorganisms exhibited completely different association behaviors with uranium. While a pure biosorption process took place with Brachybacterium sp. G1 cells, a multistage association process occurred with the archaeon. In addition to batch experiments, in situ attenuated total reflection Fourier-transform infrared spectroscopy was applied to characterize the U(VI) interaction process. Biosorption was identified as the dominating process for Brachybacterium sp. G1 with this method. Carboxylic functionalities are the dominant interacting groups for the bacterium, whereas phosphoryl groups are also involved in U(VI) association by the archaeon H. noricense.

Microbial interaction with and tolerance of radionuclides: underlying mechanisms and biotechnological applications

“…Wild-type cells with bound extracellular polymeric substances (EPS) were found to sorb more efficiently than cells without EPS in the case of Pu(V). Another example is the sorption of U(VI) by microorganisms, reported widely owing to electron microscopy (Bader et al, 2018;Povedano-Priego et al, 2019;Kolhe et al, 2020). SEM images of the yeast Yarrowia lipolytica exposed to uranyl carbonate clearly showed the apparition of uranyl deposits attached to the cell surfaces, due to biosorption and biomineralization processes (Kolhe et al, 2020).…”

Emerging Trends in Biological Treatment of Wastewater From Unconventional Oil and Gas Extraction

“…Besides reduction of organic matter, biological treatment may help in recovery of rare elements and bioprospecting. Microbes cope with the stresses of heavy metal and radionuclide exposure by several mechanisms including biosorption, bioaccumulation, biotransformation and biomineralization (Bader et al, 2018;Kolhe et al, 2018). While adsorption and accumulation of heavy metals and radionuclides in biomass may create a problem for disposal, understanding and harnessing these processes can potentially help us design better and more sustainable technologies to recover different elements from the NaCl-rich FPW and brines.…”

Diversity and Niche of Archaea in Bioremediation

“…The archaeon Halobacterium noricense DSM15987 was found to accumulate U IV with phosphoryl and carboxylate groups compared to a direct biosorption process with the bacterium Brachybacterium sp. G1 [ 127 , 128 ]. These results show promise that the haloarchaea can be used in the treatment of hypersaline environments and wastewaters for heavy metal removals.…”