Biomining: Panning for Gold with Viruses

A QUANTUM OF SCIENCE

How can viruses solve an industrial mining problem?


One of the most abundant forms of life on earth is a humble virus called a bacteriophage. Phage for short, it exists only to infect bacteria; they are harmless to plants and animals. But scientists have long used phage as a way to search for special protein sequences with unique properties – in this case, the ability to selectively bind to specific metal ores.

An emerging technology, gold- and silver-binding phages were known in the literature but only as curiosities until a scientist at the University of British Columbia Institute of Mining Engineering wondered if he could find a phage that bound copper sulfide.

Industrial mining practices typically grind ore into a fine powder to aid in separating the ore of interest from other minerals. Special chemicals called flotation aids are added to this liquid slurry of various minerals and make the copper sulfide particles hydrophobic. These particles then adhere to bubbles in the slurry and float to the top, making a solid layer of the desired ore that can easily be extracted.

The problem comes in when very similar ores are present in the same slurry. To solve this problem, Dr. Scott Dunbar of UBC decided to search for a phage that selectively bound the mineral chalcopyrite (CuFeS2). In collaboration with scientists at the UBC’s Centre for Blood Research and the Department of Biochemistry and Molecular Biology, Dunbar found three unique phages that bound tightly and selectively to chalcopyrite, sphalerite (ZnS), or both. Using these selective phages, researchers were able to enrich ore slurries for the desired mineral ore, even in the presence of the other – in effect, panning for gold among the sand.

From this similarity the term biomining was coined.

Not only the mining industry may benefit from this advance. In addition to the reduction or elimination of flotation reagents from the industrial mining process (a potent source of environmentally unfriendly chemicals), this achievement demonstrates the potential for ore-binding phages as a powerful bioremediation technology. Heavy metals such as lead and cadmium could be more easily removed from contaminated soils using similar phages, and even some nuclear wastes might be amenable to biomining remediation. As an innovative technology, biomining has capabilities that are only just beginning to be imagined, let alone tapped.

For further information:

Virus may lend a hand in copper mining


Biomining with bacteriophage: Selectivity of displayed peptides for naturally occurring sphalerite and chalcopyrite (Curtis et al)


© A Quantum of Science / P. Smalley
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