Diversity and Functional Activity of the Microbial Community in Reservoirs Containing Radioactive Wastes

In this work, diversity and potential functional activity of microorganisms in samples from the surface reservoirs used for liquid radioactive waste (LRW) storage (Seversk, Tomsk region, Russia) were investigated. The bottom sediments of water reservoirs (WR) accumulated radionuclides and heavy metals, while the water contained nitrates and other macrocomponents. The 16S rRNA gene amplicon sequencing revealed the dominance of bacteria from the phyla Pseudomonadota, Cyanobacteriota, and Actinomycetota, probably due to the high redox potential of the environment. Sulfate-reducing and methanogenic prokaryotes were minor components of the microbial communities. High number of denitrifying bacteria (up to 106 cells mL−1) can lead to the reduction of nitrates to molecular nitrogen and a decrease in the environmental Eh; that must be taken into account in technical activities for long-term conservation of the storage facilities.