AUTHOR=Ishida Yoshiki , Zhang Chongkai , Satoh Katsuya , Ito Masahiro 

TITLE=Physiological importance and role of Mg2+ in improving bacterial resistance to cesium

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1201121

DOI=10.3389/fmicb.2023.1201121

ISSN=1664-302X

ABSTRACT=<p>Cesium (Cs) is an alkali metal with radioactive isotopes such as <sup>137</sup>Cs and <sup>134</sup>Cs. <sup>137</sup>Cs, a product of uranium fission, has garnered attention as a radioactive contaminant. Radioactive contamination remediation using microorganisms has been the focus of numerous studies. We investigated the mechanism underlying Cs<sup>+</sup> resistance in <italic>Microbacterium</italic> sp. TS-1 and other representative microorganisms, including <italic>Bacillus subtilis</italic>. The addition of Mg<sup>2+</sup> effectively improved the Cs<sup>+</sup> resistance of these microorganisms. When exposed to high concentrations of Cs<sup>+</sup>, the ribosomes of Cs<sup>+</sup>-sensitive mutants of TS-1 collapsed. Growth inhibition of <italic>B. subtilis</italic> in a high-concentration Cs<sup>+</sup> environment was because of a drastic decrease in the intracellular potassium ion concentration and not the destabilization of the ribosomal complex. This is the first study demonstrating that the toxic effect of Cs<sup>+</sup> on bacterial cells differs based on the presence of a Cs<sup>+</sup> efflux mechanism. These results will aid in utilizing high-concentration Cs<sup>+</sup>-resistant microorganisms for radioactive contamination remediation in the future.</p>