Martian conditions are unsurprisingly unkind to kombucha cultures – however, a bacterial species within the culture survives and maintains its capacity to produce cellulose, experimenters have found. This not only means that cellulose could be an indicator of life beyond the Earth, but it could also be a way to protect microbial life in hostile environments, forming the first stage of efforts to terraform other worlds.
To many, kombucha is just a beverage people drink for coolness points or supposed gut benefits (aside from people who really like drinking vinegar). To microbiologists, however, there's a scientific goldmine in the biofilm of symbiotic yeasts and bacteria that ferment sugars to produce gluconic and acetic acid along with various enzymes and other small molecules.
Kombucha culture dynamics are so interesting that a team of scientists sent dehydrated kombucha biofilm to the International Space Station (ISS) in 2014 to see how microgravity affected its growth.
Some of this material was placed under a Martian-type atmosphere for 18 months while exposed to space radiation on the outside of the ISS before being returned to Earth and cultivated for another two and a half years. Constituent genomes were then compared with less-traveled counterparts.
The outcome has been published in Frontiers in Microbiology.
As in every symbiotic community, different microbes in the Kombucha culture perform different roles. The bacteria Komagataeibacter oboediens produces cellulose, best known for forming the cell walls of plants and most of cotton fiber.
Whereas other community members died on exposure to space radiation and an almost pure CO2 atmosphere, Komagataeibacter survived in a state to produce more cellulose once it was returned to a more inviting environment. Moreover, on return to Earth, its genome was very similar to the so-called ground sample on most measures.
Exceptions were the length of plasmids (extrachromosomal DNA) and the location of CRISPR-associated proteins' genes, but the paper notes; “These differences [...] do not affect any genetic metabolic profile of the cellulose synthesis.” The authors add; “This suggests that K. oboediens is a strong candidate for cellulose production in Mars colonies’ industry.”
Kombucha has been studied before as a possible probiotic drink for astronauts on long space journeys – however, its potential for cellulose production is much more important.
To the biofilm, cellulose acts as a barrier against rival microbes and protection against oxygen diffusion and ultraviolet radiation. The authors suspect the cellulose shield is why K. oboediens survived its ordeal. To Mars colonists, cellulose represents an opportunity to make fibers for clothes, paper, etc, and to protect nitrogen-fixing organisms, the key to making Martian soils suitable for growing food.
This also raises the possibility that extraterrestrial life in harsh conditions may have discovered a similar trick. Searches for pre-existing life on Mars or other worlds with little atmosphere could look for the presence of cellulose to indicate life.
There's one downside to the results, however. Genes for antibiotic resistance were increased in the space-traveling bacteria, adding an extra danger to future journeys.