Bioremediation of radionuclides by plant-microbe system: current progress and challenges

Radionuclides (isotopes of uranium, cesium, chromium, strontium, tritium, plutonium, radium, etc.) generated during nuclear fission, explosion, and research activities persistently contaminate the ecosystem, interfere with food-web, and are hazardous for human health. Some algae, fungi, bacteria, and plants have the potential to degrade the radionuclides or affect their solubility, bioavailability, and mobility. The mechanism of bioremediation deployed by the microorganisms is biotransformation, bioaccumulation, biosorption, bioprecipitation, biofilm formation, and siderophore-mediated remediation (biomineralization/immobilization). Phytoremediation (cost-effective green technology) involves phytoextraction, phytovolatilization, rhizofiltration, phytostabilization, and phytostimulation to efficiently ameliorate the radioactive pollution. The native or genetically engineered microorganisms and plants (hyperaccumulators) harboring novel genes/proteins (DrPhoN, NiCoT, phoK, ChrR6, merA, czc, fccA, ctyc3, PpcA, etc.) can cooperatively enhance remediation of radionuclides on a large scale. Meticulous researches on the molecular mechanisms of microbe-assisted transformation of radionuclides using “-omics”-based strategies for cell-free bioremediation can efficiently facilitate the removal of radionuclides from the environment in a sustainable way.