Biologically-induced precipitation of minerals in a medium with zinc under sulfate-reducing conditions

Sulfate-reducing microbial communities were enriched from soils collected in areas with crude-oil exploitation. Cultures were grown in modified Postgate C medium and minimal medium, with ethanol or lactate as an electron donor. The batch cultures were grown with addition of zinc in concentrations of 100–700 mg/l. A lack of increased protein concentration in the solutions compared with the control batch, was noted in cultures containing over 200 mg Zn²⁺/l. The 16S rRNA method was applied to determine the specific composition of the selected microorganism communities. The analysis indicated the presence of Desulfovibrio spp., Desulfobulbus spp. and Desulfotomaculum spp. in the communities. Diffractometric analysis indicated the presence of biogenic sphalerite in cultures with 100 and 200 mg Zn²⁺/l and elemental sulfur in cultures with 200 mg Zn²⁺/l. Other post culture sediments (300−700 mg Zn²⁺/l) contained only hopeite [Zn₃(PO₄)₂‧4H₂O] formed abiotically during the experiment, which was confirmed by studies of the activity of sulfate-reducing microbial communities.