Molecular Mechanisms Underlying Bacterial Uranium Resistance

Abstract

Environmental uranium pollution due to industries producing naturally occurring radioactive material or nuclear accidents and releases is a global concern. Uranium is hazardous for ecosystems as well as for humans when accumulated through the food chain, through contaminated groundwater and potable water sources, or through inhalation. In particular, uranium pollution pressures microbial communities, which are essential for healthy ecosystems. In turn, microorganisms can influence the mobility and toxicity of uranium through processes like biosorption, bioreduction, biomineralization, and bioaccumulation. These processes were characterized by studying the interaction of different bacteria with uranium. However, most studies unraveling the underlying molecular mechanisms originate from the last decade. Molecular mechanisms help to understand how bacteria interact with radionuclides in the environment. Furthermore, knowledge on these underlying mechanisms could be exploited to improve bioremediation technologies. Here, we review the current knowledge on bacterial uranium resistance and how this could be used for bioremediation applications.

Keywords: bioremediation; efflux systems; phosphatases; reduction; regulation.

FIGURE 1

Bacterial interactions with uranium. Uranium minerals are presented as UO₂CO₃ or MUO₂PO₄ with M indicating a metal ion. Pho, phosphatase; poly-P, polyphosphate granules.

FIGURE 2

Bacterial uranium reduction mechanisms. DH, Dehydrogenase; Q, quinone; cyt, cytochrome; FMN, flavin mononucleotide.

FIGURE 3

Overview of bacterial efflux systems HME-RND, CDF, and P-type ATPase.