Abstract
Bioleaching is the mobilization of metal cations from insoluble ores by microorganisms. Biofilms can enhance this process. Since Sulfobacillus often appears in leaching heaps or reactors, this genus has aroused attention. In this study, biofilm formation and subsequent pyrite dissolution by the Gram-positive, moderately thermophilic acidophile Sulfobacillus thermosulfidooxidans were investigated. Five strategies, including adjusting initial pH, supplementing an extra energy source or ferric ions, as well as exchanging exhausted medium with fresh medium, were tested for enhancement of its biofilm formation. The results show that regularly exchanging exhausted medium leads to a continuous biofilm development on pyrite. By this way, multiply layered biofilms were observed on pyrite slices, while only monolayer biofilms were visible on pyrite grains. In addition, biofilms were proven to be responsible for pyrite leaching in the early stages.
Highlights
The term of bioleaching refers to mobilization of metal cations from insoluble ores by microorganisms [1,2]
Ferrous ions can be re-oxidized to ferric ions by iron-oxidizing bacteria, and reduced inorganic sulfur compounds (RISCs) can be oxidized to sulfuric acid by sulfur-oxidizing bacteria
Contact leaching is seen to be more efficient. This may be because extracellular polymeric substances (EPS), secreted by bacteria, accumulate ferric ions via complexation and decrease the reaction distance between the cells and the mineral surface [4]
Summary
The term of bioleaching refers to mobilization of metal cations from insoluble ores by microorganisms [1,2]. Contact leaching is seen to be more efficient This may be because extracellular polymeric substances (EPS), secreted by bacteria, accumulate ferric ions via complexation and decrease the reaction distance between the cells and the mineral surface [4]. Gram-positive, generally non-motile, rod shaped, endospore-forming and moderately thermophilic acidophiles They can oxidize ferrous iron, RISCs such as tetrathionate, thiosulfate and elemental sulfur, as well as sulfide minerals in the presence of 0.02% yeast extract. Extensive oxidization of metal sulfides by biofilms of Sb. thermosulfidooxidans was indicated by the etch pits appearing within 94 h on pyrite surfaces [13] All of these studies indicate that the biofilm formation by Sulfobacillus probably leads to a high mineral dissolution rate. This study first demonstrates a method for enhancing biofilm formation by Gram-positive acidophiles and provides a hint of interfacial interactions between these bacteria and pyrite
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
