It is a well-known fact that if humanity wishes to explore deep space and live and work on other planets, we must bring Earth’s environment with us. This includes life support systems that take advantage of biological processes, also known as. Bioregenerative life support systems (BLSS), but also the numerous species of microbes that are essential for living systems. Humans already bring microbes with them when they travel to space, particularly to the International Space Station (ISS). These microbes become part of the natural environment, sticking to surfaces, growing in nooks and crannies, and getting into everything.
Given their constant presence, it is essential that we understand how they survive in space. Additionally, they have potential uses that could allow for greater self-sufficiency in space. For example, certain types of bacteria and fungi extract minerals from rocks as a source of nutrients. In a recent study aboard the ISS, researchers from Cornell and the University of Edinburgh investigated how these species could be used to extract platinum from a meteorite under microgravity conditions. Their results suggest that this could be an effective method to obtain mineral resources in space and reduce dependence on Earth.
The study was led by Rosa Santomartino, assistant professor of biological and environmental engineering at Cornell University. Faculty of Agriculture and Life Sciences (CALS) and Alessandro Stirpe, research associate in microbiology at Cornell and the School of Biological Sciences at the University of Edinburgh. They were joined by researchers from Graz Medical University in Austria, Rice University, Cancer Research UK, the UK Astrobiology Center at the University of Edinburgh, Kayser Espacio Ltdaand Kayser Italy. Their study was published on January 30 in npj microgravity.
*A bioreactor, produced by the BioAsteroid project at the University of Edinburgh. Credit: University of Edinburgh*
The work was part of Bioasteroid projecta collaborative effort between the University of Edinburgh and the European Space Agency (ESA). This project is led by Charles Cockell, professor of astrobiology at the University of Edinburgh and lead author of the study. Cockell and his colleagues developed “biomining reactors” that were deployed to the ISS in late 2020 and early 2021 to investigate how gravity affects the interaction between microbes and rocks in microgravity.
These reactors contained samples of an L chondrite asteroid that were treated with the bacteria Sphingomonas desiccabilis and the fungus Penicillium simplicissimum. These microbes show promise for resource extraction because they produce carboxylic acids that bind to minerals and release them from rocks. However, there is still some ambiguity about how this mechanism works. To this end, the experiment also included a metabolomic analysis, in which a part of the liquid culture was extracted and analyzed for biomolecules and secondary metabolites. As Santomartino said in a Cornell Chronicle Press Release:
This is probably the first experiment of its kind on the International Space Station. [a] meteorite. We wanted to keep the approach personalized, but also general, to increase its impact. They are two completely different species and will extract different things. That’s why we wanted to understand what and how, but keep the results relevant to a broader perspective, because not much is known about the mechanisms that influence microbial behavior in space.
The experiment was conducted aboard the ISS by NASA astronaut Michael Scott Hopkins while researchers performed their own control version in the laboratory. This allowed them to examine how the experiment would work in microgravity compared to Earth’s gravity. Santomartino and Stirpe then analyzed the data from the experiment, which revealed that of the 44 different elements, 18 were extracted through biological processes. Said Stirpe:
We broke the analysis down to a single element and started asking: Well, does extraction behave differently in space compared to Earth? Are these elements extracted more when we have a bacteria or a fungus, or when we have both? Is this just noise or can we see something that maybe makes some sense? We don’t see big differences, but there are some very interesting ones.
NASA astronaut Michael Scott Hopkins performs the insertion of the experimental containers into KUBIK (left) and the six hardware units inserted into KUBIK aboard the ISS (right). Credits: ESA/NASA/
Their analysis revealed that the microbes had consistent results in both Earth’s gravity and microgravity. However, it also showed distinct changes in microbial metabolism, especially in fungal samples. In microgravity, the fungus increased its production of carboxylic acids and other molecules, leading to the extraction of more palladium, platinum and other elements. Meanwhile, the non-biological leaching experiment proved to be less effective in microgravity than on Earth. Santomartino said:
In these cases, the microbe does not enhance the extraction itself, but maintains the extraction at a constant level, regardless of gravity conditions. And this is not valid only for palladium, but for different types of metals, although not for all. In fact, I think another complex but very interesting result is that the extraction rate varies greatly depending on the metal being considered and the microbial and gravity conditions.
This experiment has successfully demonstrated the potential of “biomining”, which could be used by future astronauts exploring the Moon and Mars. In addition to life support systems that rely on cyanobacteria and other photosynthetic organisms to clean the air and generate edible algae, microbes and fungi could be used to leach minerals from local regolith. These, in turn, could be used to generate building materials for structures and tools, reducing the amount of supplies that must be shipped from Earth.
Additionally, biomining has potential applications here on Earth, providing a biological means to extract metals in resource-limited environments or from mining waste. This technique could also lead to biotechnologies that facilitate the emergence of a zero-waste circular economy. But the team cautions that more research is required, as there are many variables and uncertainties about the impact space has on microbes.
“Depending on the microbial species, the space conditions, the method the researchers are using, everything changes,” Santomartino said. “Bacteria and fungi are so diverse, relative to each other, and space conditions are so complex that, at present, no single answer can be given. So perhaps we need to do more research. I don’t want to be too poetic, but to me, this is a bit [of] the beauty of that. It is very complex. And I like it.”
Additional reading: Cornell Chronicle, npj microgravity.