The process by which cyanobacteria take nutrients from rocks in the Atacama Desert has inspired ways that microbes could help build colonies on the Moon and Mars.
Researchers from the Department of Materials Science and Engineering at UCI (University of California Irvine) and the Department of Biology at Johns Hopkins University used high-resolution electron microscopy and advanced spectroscopic imaging techniques to understand precisely how microorganisms modify both natural minerals such as synthetically manufactured nanoceramics.
A key factor, according to the scientists, is that cyanobacteria produce biofilms that dissolve magnetic iron oxide particles within gypsum rocks, subsequently transforming the magnetite into oxidized hematite.
The team’s findings, which are the subject of a paper published in the journal Materials Today Bio, could provide an avenue for new biomimetic mining methods. The authors also say they see the results as a step toward using microorganisms in large-scale 3D printing or additive manufacturing on a scale useful for civil engineering in harsh environments, such as those on the Moon and Mars.
“Through a biological process that has evolved over millions of years, these tiny miners excavate rock and extract minerals essential for physiological functions, such as photosynthesis, that allow them to survive,” David Kisailus explains in a statement. Professor of Materials Science and Engineering at UCI.
“Could humans use a similar biochemical method to obtain and manipulate the minerals we consider valuable? This project has led us down that path.”
The Atacama Desert is one of the driest and most inhospitable places on Earth, but Chroococcidiopsis, a cyanobacterium found in gypsum samples collected there by the Johns Hopkins team, has evolved “the most amazing adaptations to survive its rocky habitat.” “says co-author Jocelyne DiRuggiero, an associate professor of biology at the University of Baltimore.
“Some of those traits include the production of chlorophyll that absorbs far-red photons and the ability to extract water and iron from surrounding minerals,” he added.
Using advanced electron microscopes and spectroscopic instruments, the researchers found evidence of the presence of microbes in the gypsum by observing how the minerals they contained themselves transformed.
“Cyanobacterial cells promoted magnetite dissolution and iron solubilization by producing abundant extracellular polymeric substances, which led to dissolution and oxidation of magnetite to hematite,” DiRuggiero explained.
“The production of siderophores (iron-binding compounds generated by bacteria and fungi) was increased in the presence of magnetite nanoparticles, suggesting their use by cyanobacteria to acquire iron from magnetite.”
Kisailus said the way microorganisms process metals in his desolate home made him think about our own mining and manufacturing practices.
“When we extract minerals, we often come across ores – natural material from which minerals or metals can be economically extracted – which can pose problems for the extraction of valuable metals,” he explains. “Often we have to put these minerals through extreme processing to turn them into something of value. That practice can be financially and environmentally costly.”
Kisailus said he is now considering a biochemical approach that uses natural or synthetic analogues of siderophores, enzymes and other secretions to manipulate minerals where currently only a large mechanical crusher operates. And going one step further, he said there might also be a way to get microorganisms to use similar biochemical abilities to produce manipulated material on demand in inconvenient places.
“I call it ‘moon forming’ instead of terraforming,” Kisailus said. “If you want to build something on the Moon, instead of having to rely on people to do it, you could use robotic systems that 3D print the material and then microbes reconfigure it into something of value. This could be done without jeopardizing human lives”.
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