Simone Schopf

Investigation of Acidithiobacillus ferrooxidans in pure and mixed-species culture for bioleaching of Theisen sludge from former copper smelting.

The aim of this study was to investigate the potential of bioleaching for the treatment of an environmentally hazardous waste, a blast‐furnace flue dust designated Theisen sludge.

Influence of Citrate on Metal Dissolution and Respiration Rate of Microbial Leaching Cultures

The application of acidophilic iron oxidizing bacteria is an established technique in tank and heap leaching of mainly sulfidic minerals. Even though bioleaching is broadly studied, there are still several issues to solve. Especially, the formation of iron precipitates, leading to co-precipitation of valuable metals, as well as the inhibition due to coating, considerably decrease the leaching efficiency. Consequently, the addition of chelating agents should result in an increased dissolution rate.However, organic acids, which have chelating characteristics, are generally regarded as highly toxic for leaching bacteria. Nonetheless, we found that both the addition of sodium citrate and citric acid leads to an increased iron oxidation rate of 42% and 84%, respectively, compared to standard culture medium without citrate. Chemical leaching tests with ZnS and ferric iron showed similar concentrations of dissolved zinc with and without citrate. However, the actual leaching efficiency is yet to be evaluated.

Mineral Specific Biofilm Formation of “Acidibacillus ferrooxidans” Huett2

Recently, a novel acidophilic heterotrophic iron oxidizing bacterium belonging to the newly described genus Acidibacillus (formerly Alicyclobacillus) was isolated from a water drainage ditch in Freiberg, Germany. Bioleaching tests showed that Acidibacillus ferrooxidans Huett2 contributes to the dissolution of minerals. As microbe-mineral interactions play a crucial role in nature and enhance the reaction kinetics of the mineral dissolution, attachment of Ab. ferrooxidans Huett2 on the sulfide minerals pyrite (FeS2), chalcopyrite (CuFeS2), and chalcocite (Cu2S) is in the focus of our current investigations.

Adhesion Studies of Microorganisms on Natural Ore Material

In the course of the decline of high-grade ore deposits, new effective and eco-friendly bioleaching techniques are of interest. In-situ leaching is an auspicious method, but composition of leaching community should be adapted to the respective external conditions and the ore material. In this study several sulfidic minerals were inoculated into acidic mine water of a mine in eastern Germany, housing members of well-known iron oxidizing bacteria like Acidithiobacillus, Leptospirillum and Ferrovum. The attachment tests were performed in batch and in a continuous way at different temperatures. The analysis of the extracted DNA from adhered cells showed an enrichment of Ferrovum spp. on chalcopyrite surface under in-situ conditions at 11°C. For laboratory batch conditions an accumulation of Leptospirillum spp. was detected for adhered cells probably due to the changes of the physicochemical parameter of the mine water. In more detailed analyses we aim to elucidate possible preferential attachment of the mine water community members to certain minerals.

Draft Genome of the Heterotrophic Iron-Oxidizing Bacterium “ Acidibacillus ferroxidans ” Huett2, Isolated from a Mine Drainage Ditch in Freiberg, Germany

ABSTRACT Here, we communicate the draft genome of “Acidibacillus ferrooxidans” Huett2, a novel strain of an acidophilic, heterotrophic, iron-oxidizing bacterium belonging to the phylum Firmicutes. It was isolated from a water drainage system of a former minefield in Freiberg, Germany.