How ‘Iron Man’ bacteria could help protect the environment

MSU researchers show how microbes stand up to a toxic metal, opening the door for applications in recycling and remediation


Research News


When Michigan State University’s Gemma Reguera first proposed her new research project to the National Science Foundation, one grant reviewer responded that the idea was not “environmentally relevant.”

As other reviewers and the program manager didn’t share this sentiment, NSF funded the proposal. And, now, Reguera’s team has shown that microbes are capable of an incredible feat that could help reclaim a valuable natural resource and soak up toxic pollutants.

“The lesson is that we really need to think outside the box, especially in biology. We just know the tip of the iceberg. Microbes have been on earth for billions of years, and to think that they can’t do something precludes us from so many ideas and applications,” said Reguera, a professor in the Department of Microbiology and Molecular Genetics.

Reguera’s team works with bacteria found in soil and sediment known as Geobacter. In its latest project, the team investigated what happened to the bacteria when they encounter cobalt.

Cobalt is a valuable but increasingly scarce metal used in batteries for electric vehicles and alloys for spacecraft. It’s also highly toxic to livings things, including humans and bacteria.

“It kills a lot of microbes,” Reguera said. “Cobalt penetrates their cells and wreaks havoc.”

But the team suspected Geobacter might be able to escape that fate. These microbes are a hardy bunch. They can block uranium contaminants from getting into groundwater, and they can power themselves by pulling energy from minerals containing iron oxide. “They respire rust,” Reguera said.

Scientists know little about how microbes interact with cobalt in the environment, but many researchers — including one grant reviewer — believed that the toxic metal would be too much for the microbes.

But Reguera’s team challenged that thinking and found Geobacter to be effective cobalt “miners,” extracting the metal from rust without letting it penetrate their cells and kill them. Rather, the bacteria essentially coat themselves with the metal.

“They form cobalt nanoparticles on their surface. They metallize themselves and it’s like a shield that protects them,” Reguera said. “It’s like Iron Man when he puts on the suit.”

The team published its discovery in the journal Frontiers in Microbiology, with the research article first appearing online in late November, 2020. The Spartan team included Kazem Kashefi, an assistant professor in the Department of Microbiology and Molecular Genetics, and graduate students Hunter Dulay and Marcela Tabares, who are “two amazing and relatively junior investigators,” Reguera said.

She sees this discovery as a proof-of-concept that opens the door to a number of exciting possibilities. For example, Geobacter could form the basis of new biotechnology built to reclaim and recycle cobalt from lithium-ion batteries, reducing the nation’s dependence on foreign cobalt mines.

It also invites researchers to study Geobacter as a means to soak up other toxic metals that were previously believed to be death sentences for the bacteria. Reguera is particularly interested in seeing if Geobacter could help clean up cadmium, a metal that’s found in industrial pollution that disproportionately affects America’s most disadvantaged communities.

“This is a reminder to be creative and not limited in the possibilities. Research is the freedom to explore, to search and search and search,” Reguera said. “We have textbook opinions about what microbes can and should do, but life is so diverse and colorful. There are other processes out there waiting to be discovered.”


This work was supported by the NSF’s Geobiology and Low-Temperature Geochemistry Program, as well as a Hatch project grant from the United States Department of Agriculture’s National Institute of Food and Agriculture.

(Note for media: Please include a link to the original paper in online coverage:

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John Tillman
January 8, 2021 2:10 pm

I love that photo!

Rapidly evolving bacteria put human intelligence and diligence to shame.

Reply to  John Tillman
January 8, 2021 3:35 pm

Superior fitness function? Be fruitful is one.

John Tillman
Reply to  n.n
January 9, 2021 10:22 am

Multiply and mutate: a winning strategy since 4,000,000,000 BC.

Paul Seward
January 8, 2021 2:25 pm

What about the Iron woMan bacteria?

John Tillman
Reply to  Paul Seward
January 8, 2021 3:02 pm

That would be Tungsten Man.

Reply to  John Tillman
January 8, 2021 4:36 pm

There was a “Love American Style” skit about the Man of Aluminum.

Clyde Spencer
Reply to  Paul Seward
January 8, 2021 4:59 pm

I think that the new politically correct designation will be something along the lines of gender-neutral “Iron Being” or “Ferrous Primate.” “Person” has historical overtones of maleness.

January 8, 2021 4:14 pm

Respires rust?

 the model laboratory representative Geobacter sulfurreducens grew with CoCl2 concentrations (1 mM) typically used to enrich for metal-resistant bacteria from contaminated sites.”

Oh, the model laboratory?

“In addition, G. sulfurreducens upregulated respiratory chains that could have contributed to the reductive mineralization of the metal on the cell surface.”

I read that to mean, the cyanobacteria might form a cobalt coating…

“These complex adaptive responses confer on Geobacter a competitive advantage for growth in metal-rich environments that are essential to the sustainability of cobamide-dependent microbiomes”

Now there is a mouthful of meaningless long words; “competitive advantage for growth in metal-rich environments“.

I believe these researchers need to capture a substantial amount of industry usable cobalt via their cyanobacteria as proof.

January 8, 2021 4:35 pm

It’s Oumuamua.

Peta of Newark
January 8, 2021 4:56 pm

I’m still just hatching this theory but here goes, a few aspects.

1) Like the place Gafsa in Tunisia. What was an epic phosphorus mine before we dug it all up.
Apparently created by a large inland sea the repeatedly filled up, dried out, filled up again etc etc. The creatures in the lake absorbed the minerals needed for their growth but as the lake dried out, they retreated to what was the deep end and perished when the lake did dry up completly. Each time leaving a greater and greater amount of, in this case phosphorus at that ‘place’
Did something like that occur to create the Cobalt mines we have, and myriad other ‘concentrations’ of useful stuff?

That was just a curiosity.

2) Wouldn’t these bacteria, once loaded up with their toxic cargo and wherever they go and whatever their cargo, be about as welcome as a Suicide Bomber at The Teddy Bear’s Picnic.

Surely, wherever they go ‘loaded’ with poison, they are going to destroy anything and everything that might become their own food. They have a built in Death-Wish and thus, while maybe= Iron-Men, they are incredibly dumb & stupid with it.
I think most women might agree with me on that ;-D

A bit like Ebola. A horrible and fast acting toxin but that is its weakness. Everyone can see it coming and get out of its way, even us!!!
Usually. Unless the BBC is there filming (Like Attenborough and The Walrus)

But otherwise, these folks are developing another Terrorist’s Dream Come True- just like electric cars will be.
Bacterial Novichok if you like that the average Joe Nobody could brew up in his own back-yard without anybody noticing

Take those thoughts into the present pandemic.
Sleep well

Again I say, we are on the cusp of doing something sooooo stoopid that we wipe ourselves out

Last edited 1 year ago by Peta of Newark
January 8, 2021 5:14 pm

Here is 2006 article: “Study: Bacteria Eats Toxic Waste”

January 8, 2021 6:43 pm

Fungal biological remediation for metals, including cobalt, is already quite well studied.

Reply to  gringojay
January 9, 2021 3:58 am

Paul Stamets TEDtalks are excellent as are the utoob clips

Harri Luuppala
January 8, 2021 8:50 pm

In Finland we have already a mine using microbes to extract metal incl. cobolt from ore. Process is called bioleaching. First bacters in ore was found 1949. It is well known and proven process for large scale extraction and they sell also this know-how 🙂

In our cold climate it takes 1,5y for bacters to do their part of the process to extract metals from ore. So if you start today, then year 2022 you will have metals from ore – or actually enriched for the next heap (chemical one).

Their page is not very informative on the process, but some details are there. It has been very expensive learning process to start and roll-out working process for this mine!


Btw. They have 6700 km – 4200 miles – pipes circulating air and water based fluid in the bacteria heap!

For enthustiastics to translate details (last page) from a Finnish Chemistry magazine:

Last edited 1 year ago by Harri Luuppala
Geoff Sherrington
January 9, 2021 1:48 am

We were using filtration of mine waters by percolation through local soils in uranium mining ar Ranger One in the Top End of the NT of Australia in the early 1980s. In the 1970s we were looking at bacterial ways to convert sulphur-containg mineral mixes like soil and crushed rock ino a uniform chemistry like sulphate ions, to make subsequent chemical analysis easier with the instruments then available. One bacterium was Desulfovibrio desulfuricans. The ideas were fairly easy to come up with, but putting them into practice was nuch harder than expected.

Geoff Sherrington
January 9, 2021 2:04 am

I deplore the tone of the press release that semi-automatically seems to leap to words like “toxic” (5 mentions in the release) and the woke-approved “incredible feat” and “thinking outside the box” and ““It’s like Iron Man when he puts on the suit” and finally the scare tactic for cobalt “It’s also highly toxic to livings things, including humans and bacteria. “

Too many modern writers fail to grasp the significance of
the work Paracelsus which Wiki records loosely as “Nearly
500 years ago, Swiss physician and chemist Paracelsus expressed the basic
principle of toxicology: ‘All things are poison and nothing is without poison;
only the dose makes a thing not a poison’.”

This release seems to be written for intellects of
10-year-olds starting the journey of scientific discovery. Alas, too much
modern literature associated with “the environment”,
“pollution”, “danger”, “remediation”,
“prevention” and so on is at this level. Horrible.

Geoff S

Reply to  Geoff Sherrington
January 9, 2021 8:45 am

yup, even water is poison if you drink enough

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