Biomining: Bacteria 'Mine' Copper

Very cool concept to harvest metals. Microbiology is an underestimated force and is such an integral part of the geography we live in. The chemistry of aquifers can never be truly understood or interpreted without adding the microbial factor. I view geomicrobiology and geochemistry as a passion and they never fails to interest. Thanks for sharing.

Interesting but questionable about possible side affects to humans. A copper company in Southwestern USA that I did some work for a few years back has been experimenting with this method of extraction. They encountered some very lethal results when employee(s) were exposed to a leak and absorbed some of the bacteria into their internal systems. The survival rate for humans when exposed appears to be extremely "low to none" with no antidote available yet to counteract the affects. Do you suppose they were/are using the same strain of bacteria for their research? If so; it can't be good for humans nor the environment as I have yet to observe any mining process that does not have pump, conveyor, and valve leaks on a continual basis.

One thing that could be toxic is the copper itself. Copper consumption does not have to be very high to induce vomiting (1 mg/L), so I would imagine consuming several grams could be harmful to kidneys and liver ( lethal toxic levels are in the 50 or 60 mg/L range. I would expect the cure would be to make sure the person receives induced vomiting and stomach pump. I am aware of bacteria inducing metal releases into water ground water supplies and many of them are simply sulphate reducing bacteria (SRB). If there is little available supply of SO4 (sulphate), the SRB will actually harvest the bedrock ore. Barium sulfate or lead sulphate ores will release barium or lead into the water. Barium release is quite common by this method and lead although less common does happen naturally in wells through microbial reduction of the ore.

Regarding microbial copper reduction, I am not sure what types of bacteria would be required and that may depend on the form of the copper ore. Many copper ores are carbonates (CO3) or Sulphide (S) bound. Methane bacteria would be the most common biological mechanism and these methane bacteria are not toxic in themselves. Methane can be dangerous due to ignition capabilities. Some iron bacteria may also be involved in some sort of consortium of microorganisms. This is not unlike many of the biofouled wells we have encountered. The biofilms are often a consortium of bacteria and the underlying layer of the biofilm has a very low pH. The availability of the underlying ores are then very susceptible to release of toxic metals into the well water.

I remain suspicious of the metal "copper" creating the toxicity and not the microorganism itself. Keeping your mouth covered is a good practice if working around any leaking pipes used in mining copper.

I will say that in 42 years of ground water sampling, I have only had one well come back with levels of copper greater than 1 mg/L. Many more were elevated in copper but not to the toxic levels. It does point out the need to sample water wells for extensive testing at accredited labs to identify the metals and biofouling potential. Most private wells have received very little testing other than the standard coliform tests.

Good feedback, thanks.

I do know it was not the copper content that caused the health issues (fatality).

There was a very limited explanation from the mining company identifying the damage inflicted as a direct reaction to the bacteria in the body and the area was quarantined.

It is now a very restricted site with bio-hazard full suit PPE requirements prior and during entry with three level personal cleanup required when exiting. (Much akin to nuclear exposure cleanup requirements.)

Pretty scary scenario.

According to the article I referred in the previous post, there are no toxic metabolites that should form from the bacteria using that process (M. trichosporium). There may also be other processes employing other types of microorganisms but I can't think of any without resorting to lots of research and time. My mentor has had a stroke and unfortunately I can't discuss this issue with him.

One other thing that strikes me as a possibility is the acid used and perhaps there was some direct internal contact with a strong acid. Now that could destroy a lot of internal membranes. It is interesting and if you find out what it is, I would be curious enough to want to know the answer. I am retired but still do some rare consulting and maintain my own interest. Cheers.

I agree with kevinm, there's no chance that this bacterium would cause harm by ingestion or by infection. Thiobacillus ferrooxidans and its relatives are adapted to highly acidic environments, and to gaining their energy by metabolising iron and sulphur compounds - they simply are not adapted to survive in the human body conditions at all.

I did find this species linked to the 'chinese drywall' mystery though, and that may be a clue to the cause of harm in that case. Sulphurus emissions are noxious - and if there's lots of sulphur to be metabolized in the ore you were talking about, adding acid and getting a big batch of bacteria going, could cause an unexpectedly nasty biohazard from sulphur gases. In fact, since addition of acids is typical of the bioleaching process, I'd guess sulphur gases mixed with acid fumes... yes that could kill you, and you wouldn't want to go there without a suit.

The only bad thing I have to say about T. ferrooxidans and its buddies is... don't feed em sulphur!

These bacteria are amazing... I stumbled on these while reading about bog iron the past winter. It was a key source of metal in times past - especially in the north. A bog could be harvested for iron every thirty years or so..

http://www.hurstwic.org/history/articles/manufacturing/text/bog_iron.htm

You would probably find this discussion interesting, about T. ferrooxidans in bog iron formation, and also its less helpful effects on water pipes and oil equipment, etc.

And now it can be used in micromachining as well..

Iron Bacteria are interesting and do play a pivotal role in a lot of life going back to helping create atmospheres that we can breathe on earth. I have been to L'Anse aux Meadows in Newfoundland and witnessed much of the bog iron you referred. Peat was a common construction material used by the Vikings in this treeless area. About 10 years ago, I also stayed in nearby cabins serviced by a ground water well. I was very impressed by the microbial colonization in the toilet reservoir ( One of my habits staying in a rural motel or resort is to look in the reservoir of the toilet. One can learn a lot about the water supply just by observation). The toilet reservoir had at least 1/2 inch of slime deposit on its wall. That level of colonization (much more than normally observed) tells me that the ground water had a very high level of total organic carbon (TOC). Bacteria will use the iron as a means of respiration (electron donation) and thus you end up with lots of iron in the water supply. The available TOC is the food source. These microbes present no health problem directly but could harbour other forms of bacteria. It is quite a common water well problem and can be controlled by periodic disinfection of the well with bleach. We would use hydrogen peroxide as it formed a lot of oxygen gas that would help agitate and remove the bacteria from the side of the borehole. Looking in the reservoir is a good measure of some water quality.

The bacteria are facultative in that they can thrive in aerobic and anaerobic conditions. Within the past couple of decades iron bacteria called simply 178 after the depth in a well they were found, were isolated that would take oxidized iron and put it back into solution. This helps to explain the reason you can get very high levels of iron in a water supply. Good reads are Roy Cullimore or Francis Chappelle who have spent a lot of time working in the ground water microbial field. Still no mention of an toxicity by any of these bacteria. I would guess some other more toxic bacteria found an opportunity and joined the consortium created from the copper process. It is possibily caused by some neurotoxin from the metabolites of that opportunistic bacteria.