The quest for sustainable space exploration is pushing scientists to consider unconventional allies: microbes. From supporting life support systems to potentially extracting valuable resources, bacteria and fungi are emerging as key components in humanity’s plans to live and function beyond Earth. A recent study conducted aboard the International Space Station (ISS) demonstrates the potential of “biomining” – using microorganisms to extract metals from asteroids – a process that could significantly reduce our reliance on Earth-based resources for future space missions.
Researchers from Cornell University and the University of Edinburgh investigated whether Sphingomonas desiccabilis and Penicillium simplicissimum, two species known for their mineral-extracting capabilities, could effectively harvest platinum from a meteorite sample in the unique environment of microgravity. The findings, published January 30th in npj Microgravity, suggest that these microbes could play a crucial role in establishing self-sufficient resource utilization in space, paving the way for long-duration missions to the Moon and Mars.
The study was spearheaded by Rosa Santomartino, an assistant professor of biological and environmental engineering at Cornell’s College of Agriculture and Life Sciences (CALS) and Alessandro Stirpe, a research associate in microbiology at Cornell and the School of Biological Sciences at the University of Edinburgh. The collaborative effort also included researchers from the Medical University of Graz in Austria, Rice University, Cancer Research UK, the UK Centre for Astrobiology at the University of Edinburgh, Kayser Space Ltd, and Kayser Italia.
The research was part of the larger BioAsteroid project, a partnership between the University of Edinburgh and the European Space Agency (ESA), led by Charles Cockell, a professor of astrobiology at the University of Edinburgh. The project utilized specially designed “biomining reactors” deployed to the ISS in late 2020 and early 2021 to study the interaction between microbes and rock in microgravity. These reactors contained samples of an L-chondrite asteroid, a common type of meteorite, treated with the selected bacteria and fungus.
A bioreactor produced by the BioAsteroid project at the University of Edinburgh. Credit: University of Edinburgh
How Microbes Extract Metals
Sphingomonas desiccabilis and Penicillium simplicissimum were chosen for their ability to produce carboxylic acids, which bind to minerals and release them from rocks – a process known as bioleaching. While the mechanism isn’t fully understood, the experiment included a metabolomic analysis to identify the biomolecules and secondary metabolites involved in the extraction process. As Santomartino explained in a Cornell Chronicle press release, the team aimed for a broad approach, recognizing the limited understanding of microbial behavior in space. “These are two completely different species, and they will extract different things. So we wanted to understand what and how, but retain the results relevant to a broader perspective, given that not much is known about the mechanisms that influence microbial behavior in space.”
Microgravity’s Impact on Biomining
NASA astronaut Michael Scott Hopkins conducted the experiment on the ISS, while the research team simultaneously ran a control version in a laboratory on Earth. Analysis of the experiment data revealed that 18 out of 44 different elements were extracted through biological processes. Researchers focused on comparing extraction rates in microgravity versus Earth’s gravity, and the performance of the bacterium versus the fungus, both individually and in combination.
The results showed consistent extraction rates between Earth gravity and microgravity, but notable changes in microbial metabolism, particularly with the fungus. In microgravity, the fungus increased its production of carboxylic acids and other molecules, leading to enhanced extraction of palladium, platinum, and other elements. Interestingly, non-biological leaching proved less effective in microgravity than on Earth. “In these cases, the microbe doesn’t improve the extraction itself, but it’s kind of keeping the extraction at a steady level, regardless of the gravity condition,” Santomartino noted. “And this is not just true for the palladium, but for different types of metals, although not all of them.”
Implications for Space Exploration and Beyond
This successful demonstration of biomining has significant implications for future space exploration. Beyond the well-established use of cyanobacteria and other photosynthetic organisms in bioregenerative life support systems – which clean air and generate edible algae – microbes and fungi could be utilized to extract minerals from the regolith (surface material) of the Moon and Mars. These extracted minerals could then be used to create building materials and tools, reducing the need to transport supplies from Earth.
The potential benefits of biomining aren’t limited to space. The technique could also be applied on Earth to extract metals from resource-limited environments or mine waste, contributing to a more sustainable, circular economy. Though, the researchers caution that further investigation is needed to fully understand the complex interplay between microbial species, space conditions, and extraction methods. “Depending on the microbial species, depending on the space conditions, depending on the method that researchers are using, everything changes,” Santomartino said. “Bacteria and fungi are all so diverse, one to each other, and the space condition is so complex that, at present, you cannot grant a single answer.”
Future research will focus on unraveling these complexities and optimizing biomining processes for both terrestrial and extraterrestrial applications. As our ambitions for space exploration grow, harnessing the power of these microscopic allies will be critical to achieving long-term sustainability and self-sufficiency beyond our planet.
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