Canadian researchers have tested a series of miniaturized, low-cost life detection instruments in the hope that similar technology will be used to find extant life within our solar system.
In the Canadian high arctic Jacqueline Goordial and her team of field researchers shovelled away a thick blanket of snow to be able to chisel at the frozen ground beneath. The team then takes soil samples, and back at the McGill Arctic Research Station, the microbial samples are extracted and carefully pipetted into a series of life-detection instruments. The climate of the high arctic is analogous to that of Mars, and the researchers hope a similar life-detection platform might one day be used to find extant life on planetary bodies such as Mars, Europa or Enceladus.
Goordial told SpaceQ in a phone interview “we were thinking very conceptually. What would a life-detection system look like?” The instruments and techniques the researchers are testing are miniaturized, low-weight, and low cost, allowing for samples to be tested quickly in the field—important characteristics if the tools were to be sent to space.
Goordial’s research, published in Frontiers in Microbiology, differs from most previous work in that it is focused on directly detecting and analysing extant life. Previous exploration of life on other planets has typically involved searching for habitable conditions or detecting biosignatures such as nucleic acids that don’t necessarily signify that the organisms are alive.
The last time direct life-detection instruments were used in space was during the Viking missions during the 1970’s, a procedure that involved mixing Mars soil with nutrients and water and testing for respiration. The results were inconclusive.
The platform the researchers developed is able to culture micro-organisms in situ, assess microbial activity, and sequence the genomes of select strains and environmental samples. The life-detection platform consisted of three independently functioning components:
- The Cryo-iPlate allows micro-organisms from soil samples to be cultured in the field and consists of an agar-like gel that absorbs nutrients directly from the environment. Wells within the gel are inoculated with a single cell which is subsequently cultured. The successfully cultured microbes can then have their DNA extracted and sequenced.
- The Microbial Activity Microassay (MAM) is used to determine biological properties of the microbe. Each well of the assay contains a different carbon substrate (glucose, fructose, etc.) as well as a redox dye. If the micro-organism being tested is able to metabolize the substrate, then the redox dye turns purple.
- The Oxford Nanopore MinION is a small, portable nucleic acid sequencer that involves passing nucleic acids through a protein nanopore. Preparation of DNA for the sequencer takes less than twenty minutes, and the process does not require PCR amplification–a common step for most DNA sequencing procedures. Both cultured samples and direct environmental samples were sequenced with the minION.
A number of different life-detection instruments being used in concert would make evidence of other-worldly life more robust. “If we ever think we find life on other planets, it’s going to be proven by multiple different instruments and multiple different angles,” said Goordial. “There’s probably not going to be one instrument that’s the smoking gun. It’s going to have to be corroborated by several instruments that all point to the same thing.”
Using the MAM plate the researchers were able to identify an active community of microbes that could metabolize L-serine, an amino acid, and the environmental sample was sequenced using the minION.
With the cryo-iPlate the researchers obtained 39 microbial isolates, some of which are thought to be novel strains. One bacteria, a species of Pedobacter, was found to be only 96% genetically similar to other known strains. “When you’re looking at 96% you’re looking at a completely new strain that has never been seen before,” said Goordial. “Using this technology we were able to discover a putatively new species of micro-organism.”
The study, funded by the Canadian Space Agency, the McGill Space Institute, and the Natural Sciences and Research Engineering Council of Canada (NSERC), is a conceptual starting-off point but still needs further development before being space-ready. For one, sampling and intermediary steps were done by humans—if a similar platform was to be used in space, technology would have to be engineered to operate the instruments. Other research labs are working on automating DNA extraction and combining the various steps in using the instruments. In addition, the instruments themselves are rapidly being improved upon.
“The minION I think is really promising, but there are some things you’d have to consider,” said Goordial. Currently the protein-based nanopore technology won’t be able to withstand the cold temperatures and long flight times on missions to outer space. “Think how rigid protein becomes when it’s cold,” said Goordial. The NASA ColdTech program is currently developing a minION sequencer with nanopores made out of more stable materials such as graphene.
Even though the life-detection platform isn’t ready be sent on a mission to Mars yet, the instrumentation is still useful for detecting life in remote areas of earth. The tools would be able to provide information in real time and could be utilized in situations where samples might degrade during transportation. Whether or not the platform could be used to test life in the deep ocean would depend on the microbial sampling method and transport of the samples to the life-detection platform.
“The iPlate has the potential to be used anywhere,” said Goordial. 99% of micro-organisms can’t be successfully cultured, and the iPlate targets this issue by directly absorbing nutrients from the environment and culturing the microbes on the spot. “In just about every environment that we look, we can see that there’s these strange organisms there, and we’ve never cultured any of them,” said Goordial. “Ultimately the best way to find out what an organism is doing is to culture it and test it directly.”