Microbial mining could help colonize Moon and Mars, study claims

As mentioned by the university, high-resolution electron microscopy and cutting-edge spectroscopic imaging methods were used by researchers from the Departments of Materials Science and Engineering at UC Irvine and Johns Hopkins University to gain a thorough understanding of how microorganisms modify both naturally occurring minerals and artificial nanoceramics.

The authors claim that one important cause is the production of biofilms by cyanobacteria that dissolve magnetic iron oxide particles within gypsum rocks, converting the magnetite into oxidized hematite.

Their findings were published in Materials Today Bio on December 15.

“Through a biological process that has evolved over millions of years, these tiny miners excavate rocks, extracting the minerals that are essential to the physiological functions, such as photosynthesis, that enable their survival,” said corresponding author David Kisailus, UCI professor of materials science and engineering.

“Could humans use a similar biochemical approach to obtain and manipulate the minerals that we find valuable? This project has led us down that pathway.”

Why is the Atacama Desert significant?

The Atacama Desert is one of the world's driest and most hostile environments. Chroococcidiopsis, a cyanobacterium discovered in gypsum samples gathered by the Johns Hopkins team. According to co-author Jocelyne DiRuggiero, associate professor of biology at the Baltimore institution, the Atacama Desert is an extraordinary place to survive in a stony habitat.

“Some of those traits include producing chlorophyll that absorbs far-red photons and the ability to extract water and iron from surrounding minerals,” she added.

Kisailus said the way the microorganisms process metals in their desolate home made him think about our own mining and manufacturing practices. “When we mine for minerals, we often wind up with ores that may present challenges for extraction of valuable metals,” he added.

“We frequently need to put these ores through extreme processing to transform it into something of value. That practice can be monetarily and environmentally costly.”

Kisailus is now considering a biological strategy that would use natural or synthetic analogs of siderophores, enzymes, and other secretions to alter minerals where only a big mechanical crusher is now effective. Taking a step further, he suggested that there might be a method to persuade microbes to use comparable biochemical capabilities to generate an engineered substance on demand in inconvenient locations.

“I call it ‘lunar forming’ instead of terraforming,” Kisailus said. “If you want to build something on the moon, instead of going through the expense of having people do it, we could have robotic systems 3D-print media and then have the microbes reconfigure it into something of value. This could be done without endangering human lives.”

Study abstract:

Iron is an essential micronutrient for most living organisms, including cyanobacteria. These microorganisms have been found in Earth's driest polar and non-polar deserts, including the Atacama Desert, Chile. Iron-containing minerals were identified in colonized rock substrates from the Atacama Desert. However, the interactions between microorganisms and iron minerals remain unclear. In the current study, we determined that colonized gypsum rocks collected from the Atacama Desert contained both magnetite and hematite phases. A cyanobacteria isolate was cultured on substrates consisting of gypsum with embedded magnetite nanoparticles. Transmission electron microscopy imaging revealed a significant reduction in the size of magnetite nanoparticles due to their dissolution, which occurred around the microbial biofilms. Concurrently, hematite was detected, likely from the oxidation of the magnetite nanoparticles. Higher cell counts and production of siderophores were observed in cultures with magnetite nanoparticles suggesting that cyanobacteria were actively acquiring iron from the magnetite nanoparticles. Magnetite dissolution and iron acquisition by the cyanobacteria was further confirmed using large bulk magnetite crystals, uncovering a survival strategy of cyanobacteria in these extreme environments.