MICROBIAL DIVERSITY IN URANIUM-MINE WASTE HEAPS

Two different uranium mine waste heaps near Ronneburg, Thuringia, Germ any, which contain the remains of the activity of the former uranium-m ining Soviet-East German company Wismut AG, were analyzed for the occu rrence of lithotrophic and chemoorganotropic leach bacteria, A total o f 162 ore samples were taken up to a depth of 5 m. Cell counts of ferr ous iron-, sulfur-, sulfur compound-, ammonia-, and nitrite oxidizing bacteria were determined quantitatively by the most-probable-number te chnique. Sulfate-, nitrate-, ferric iron-, and manganese-reducing bact eria were also detected, In addition, the metabolic activity of sulfur - and iron-oxidizing bacteria was measured by microcalorimetry. Genera lly, all microorganisms mentioned above were detectable in the heaps. Aerobic and anaerobic microorganisms thrived up to a depth of 1.5 to 2 m, Up to 99% of Thiobacillus ferrooxidans cells, the dominant leachin g bacteria, occurred to this depth. Their numbers correlated with the microbial activity measurements. Samples below 1.5 to 2 m exhibited re duced oxygen concentrations and reduced cell counts for all microorgan isms.