BioRock, a new investigation on the International Space Station (ISS), is expected to help gain insight into the physical interactions of liquid, rocks, and microorganisms under microgravity conditions for biomining in space. In addition, data from this investigation can be used to inform the development of life support systems involving microbial components on long-duration spaceflight missions. Biorock is the first use of a prototype miniature mining reactor in space.
Fluorescence microscopy image of biofilm of Spingomonas desiccabilis — a Gram-negative, non-spore-forming bacterium, which was isolated from soil crusts in the Colorado plateau — growing over and into the surface of a basalt slide as part of the BioRock investigation. Organisms are stained with DNA binding dye Sybr Gold. Growth is seen into the rock cavities. Image credit: ESA.
Microbes growing on the surface of rocks can gradually break down those rocks and extract minerals. This natural process enables a process called biomining.
Common on Earth, biomining could eventually help explorers on the Moon or Mars acquire needed materials, lessening the need to use precious resources from Earth and reducing the amount of supplies that explorers must take with them.
“We’re studying three types of microbes, giving us the first comparison between behaviors of different microbes in the space environment,” said University of Edinburgh’s Professor Charles Cockell, principal investigator of the BioRock project.
Scientists know very little about how microgravity affects microbe and mineral interactions, but previous research demonstrates that the attachment of microbes to surfaces, or formation of biofilms, occurs differently in space.
In general, biofilms increase, grow thicker and show particular shapes and structures in microgravity.
Investigators expect to see similar behavior by the microbes in the BioRock investigation, scheduled to travel to the ISS aboard a Dragon cargo spacecraft in July 2019.
“For the investigation, we are using basalt rock that is naturally very vesicular, or contains lots of spaces, to see how the bacteria interact within these cavities in microgravity,” said Dr. Rosa Santomartino, a postdoctoral scientist at the University of Edinburgh.
Back on Earth, researchers plan to examine how the microbes grew across and into the rock and to compare the three types of microbes: Sphingomonas desiccabilis, Bacillus subtilis and Cupriavidus metallidurans.
They also will look at the elements leached into the fluid around the rock, and examine how well the different microbes extracted more than 20 different elements from the rocks.
“The BioRock experiment starts putting the pieces of the puzzle together,” Professor Cockell said.
“Understanding how microbes interact, grow and extract elements from a rock surface in microgravity and simulated Mars gravity will tell us, for the first time, if low gravity affects the ability of microorganisms to attach to rock surfaces and perform biomining. In other words, whether extraterrestrial mining is possible.”
The results should provide qualitative and quantitative comparison of bacterial and rock interactions taking place at terrestrial gravity, simulated Martian gravity, and microgravity levels.
For example, the absence of thermal convection in microgravity could restrict the supply of food and oxygen to bacteria in rocky environments and suppress their growth.
“We hope to gain insights into how microbes grow in space and how we might use them in human exploration and settlement of space, from mining to turning rocks into soils on the Moon and Mars,” Professor Cockell said.
The team’s paper was published in the October 2018 issue of the International Journal of Astrobiology.
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Claire-Marie Loudon et al. 2018. BioRock: new experiments and hardware to investigate microbe-mineral interactions in space. International Journal of Astrobiology 17 (4): 303-313; doi: 10.1017/S1473550417000234
