Physicochemical and microbiological characteristics of groundwater from observation wells of a deep radioactive liquid waste repository

A radioactive liquid waste repository was found to be the habitat of a rich microbial community with a high catabolic potential. Groundwater from a de pth of 162-189 m contained aerobic saprotrophic and anaerobic fermentative, sulfate-reducing, and denitrifying bacteria. Nitrate-reducing bacteria res iding in this groundwater were isolated in pure cultures. Based on the resu lts of their physiological studies, 16S rRNA sequencing, and phylogenetic a nalysis, the microorganisms isolated were ascribed to one phylogenetic bran ch, the gamma-subclass of gram-negative bacteria. Among six isolates, four belonged to the genus Acinetobacter whereas two others belonged to the gene ra Comamonas and Aeromonas. The data obtained indicate that the microflora of the repository can exert a certain effect on the chemical composition of the formation fluids and bearing rocks, as well as on the migration of rad ionuclides.