Differences in adhesion of A. thiooxidans and A. ferrooxidans on chalcopyrite as revealed by atomic force microscopy with bacterial probes

Diao, Mengxue, Nguyen, Tuan A. H., Taran, Elena, Mahler, Stephen and Nguyen, Anh V. (2014) Differences in adhesion of A. thiooxidans and A. ferrooxidans on chalcopyrite as revealed by atomic force microscopy with bacterial probes. Minerals Engineering, 61 9-15. doi:10.1016/j.mineng.2014.03.002


Author Diao, Mengxue
Nguyen, Tuan A. H.
Taran, Elena
Mahler, Stephen
Nguyen, Anh V.
Title Differences in adhesion of A. thiooxidans and A. ferrooxidans on chalcopyrite as revealed by atomic force microscopy with bacterial probes
Formatted title
Differences in adhesion of A. thiooxidans and A. ferrooxidans on chalcopyrite as revealed by atomic force microscopy with bacterial probes
Journal name Minerals Engineering   Check publisher's open access policy
ISSN 0892-6875
1872-9444
Publication date 2014-06
Sub-type Article (original research)
DOI 10.1016/j.mineng.2014.03.002
Open Access Status
Volume 61
Start page 9
End page 15
Total pages 7
Place of publication Kidlington, Oxford, United Kingdom
Publisher Pergamon
Collection year 2015
Language eng
Formatted abstract
Highlights
• Study of bacteria–mineral interactions relevant to bioleaching process.
• BM adhesion measured by bacteria-coated AFM colloidal probe technique.
• Adhesion of A. ferrooxidans onto chalcopyrite is stronger than A. thiooxidans.
• Both bacteria show large adhesion forces at low pH.

Bacteria capable of oxidizing sulphur and iron, known as Acidithiobacillus thiooxidans and Acidithiobacillus ferrooxidans bacteria, respectively, are important in bioleaching of sulphide minerals. Here, using atomic force microscopy (AFM) we report significant differences in the adhesion behaviour of these bacteria when interacting with chalcopyrite surfaces. The bacterial force probes were prepared by attaching bacterial cells onto a silica microsphere (∼10 μm radius) glued to the end of an AFM cantilever. Probes were brought into, and separated from, the contact with chalcopyrite surfaces in half-strength 9 K medium solutions of various pH conditions. The adhesion forces of nano-Newton resolution versus snap-off distances of nanometre resolutions between the bacterial probes and the mineral surface in aqueous media were obtained during retracting of the probes from the mineral surface. The results show generic different adhesion force curves measured for the two bacteria strains: A. thiooxidans cells exhibit a saw-tooth shaped adhesion force curve, while A. ferrooxidans cells display a stair-step adhesion force curve. Generally, A. ferrooxidans cells show stronger averaged adhesion force with chalcopyrite than A. thiooxidans. Larger adhesion forces of both bacteria were observed at low pH, close to the isoelectric points (∼pH 2) of cells and chalcopyrite. The AFM and FTIR results indicate that the polymers on the bacterial cell surface are critical to the bacterial adhesion onto mineral surfaces. These bacterial probe analyses provide novel insights into the nano-scale mechanism by which bioleaching bacteria interact with mineral surfaces.
Keyword Acidithiobacillus thiooxidans
Acidithiobacillus ferrooxidans
Chalcopyrite
Bacterial adhesion
Atomic force microscopy
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

 
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Created: Thu, 27 Mar 2014, 22:04:10 EST by Stephen Mahler on behalf of School of Chemical Engineering