Scientists have formed an unusual new alliance in the fight against climate change, using bacteria to extract rare metals that are crucial to developing green technologies. Without the help of these microbes, we could run out of raw materials to build turbines, electric cars and solar panels, they say.

The work is being led by scientists at the University of Edinburgh and aims to use bacteria that can extract lithium, cobalt, manganese and other minerals from old batteries and discarded electronic devices. These rare and expensive metals are crucial for making electric cars and other devices that green technologies rely on, says Professor Louise Horsfall, Chair of Sustainable Biotechnology at Edinburgh.

“If we want to end our dependence on petrochemicals and rely on electricity for our heating, transportation and energy, we will become more and more dependent on metals,” Horsfall said. “All those photovoltaic panels, drones, 3D printers, hydrogen fuel cells, wind turbines and electric car engines require metals – many of them rare – that are critical to their operation.”

Politics is also an issue, scientists warn. China not only controls the main supply of rare earths, but also dominates their processing. “To get around these problems, we need to develop a circular economy in which we reuse these minerals wherever possible, otherwise we will run out of materials very quickly,” said Horsfall. “There is only a limited amount of these metals on earth and we can no longer afford to throw them away as waste as we have done so far. We need new recycling technologies if we want to do something about global warming.”

And the key to this recycling is microbes, says Horsfall. “Bacteria are wonderful, crazy little things that can carry out weird and wonderful processes. For example, some bacteria can synthesize nanoparticles from metals. We think they do this as a detoxification process. Basically, they attach themselves to metal atoms and then spit them out as nanoparticles so they are not poisoned by them.”

Using such bacterial strains, Horsfall and her team have now dissolved waste from electric batteries and cars and then used bacteria to bind certain metals in the waste and separate them as solid chemicals. “First we did this with manganese. Later we did it with nickel and lithium. And then we used a different bacterial strain and were able to extract cobalt and nickel.”

Crucially, the bacterial strains used to extract these metals were naturally occurring bacterial strains. In the future, Horsfall and her team want to use gene-edited versions to increase their metal production. “For example, we need to be able to extract cobalt and nickel separately, which we are currently unable to do.”

The next part of the process will be to prove that these metals, once removed from old e-waste, can be used as components of new batteries or devices. “Then we will know if we are helping to develop a circular economy for dealing with green technologies. New laws have mandated that by the next decade, significant amounts of recycled metals must be used to make new devices with green technology. These targets will be difficult to achieve and bacteria will be crucial in making this happen.”