Martian conditions are not surprisingly unpleasant with kombucha crops; however, a bacterial species of the crop survives and maintains its ability to produce cellulose, the experimenters found. This not only means that cellulose could be an indicator of life beyond 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.
For many, kombucha is just a drink that people drink for freshness or supposed intestinal benefits (apart from people who really like to drink vinegar). For microbiologists, however, there is a scientific gold mine in the biofilm of yeasts and symbiotic bacteria that ferment sugars to produce gluconic and acetic acid along with various enzymes and other small molecules.
The dynamics of kombucha culture 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 being exposed to space radiation outside the ISS before being returned to Earth and cultivated for two and a half more years. The constituent genomes were then compared with the less traveled counterparts.
The result has been published in Frontiers in Microbiology.
Part of the platform and the kombucha biofilms used. Image credit: European Space Agency
As in all symbiotic communities, the different microbes of the Kombucha culture play different roles. The bacterium Komagataeibacter oboediens produces cellulose, best known for forming the cell walls of plants and most of the cotton fiber.
While other members of the community died from exposure to space radiation and an almost pure CO2 atmosphere, Komagataeibacter survived in a state of producing more cellulose once returned to a more welcoming environment. In addition, when it returned to Earth, its genome was very similar to the so-called terrestrial sample in most measurements.
The exceptions were the length of the plasmids (extrachromosomal DNA) and the location of the CRISPR-associated protein genes, but the paper notes; “These differences […] they do not affect any genetic metabolic profile of cellulose synthesis. “The authors add;
Kombucha has previously been studied as a possible probiotic drink for astronauts on long space travel; however, its potential for cellulose production is much greater.
As for biofilm, cellulose acts as a barrier against rival microbes and as a protection against oxygen diffusion and ultraviolet radiation. The authors suspect that the cellulose shield is why K. oboediens survived its test. For Mars settlers, cellulose represents an opportunity to make fibers for clothing, paper, etc., and to protect nitrogen-fixing organisms, the key to making Martian soils suitable for food cultivation. .
This also raises the possibility that extraterrestrial life in harsh conditions may have discovered a similar trick. Pre-existing life searches on Mars or other low-atmosphere worlds could look for the presence of cellulose to indicate life.
However, the results have a drawback. Antibiotic resistance genes were increased in space-traveling bacteria, adding an additional danger to future travel.