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| Methylobacterium jeotgali. (Aslam et al, Int. J. Syst. Evol. Microbiol. 2007) |
The number of bacterial and fungal species living among us
is continually rising, and low-gravity environments like the International
Space Station are no exception (ISS).
Researchers from the United States and India collaborated
with NASA to discover four bacteria strains residing in various locations on
the International Space Station, three of which were previously unknown to
science.
Three of the four strains were isolated in 2015 and 2016 –
one was discovered on an ISS research station's overhead panel, the second in
the Cupola, and the third on the dining table's surface; the fourth was
discovered in an old HEPA filter returned to Earth in 2011.
All four strains are members of a bacterial family found in
soil and freshwater that aid in nitrogen fixation, plant growth, and the
control of plant pathogens. Basically, beneficial bacteria to have around while
growing stuff.
You may be wondering what such soil bacteria were doing on
the International Space Station, but astronauts have been developing small quantities
of food on the station for years, so it's not shocking that we've discovered
plant-related microbes aboard.
One of the strains, the HEPA-filter find, was classified as
Methylorubrum rhodesianum, a well-known species. The strains IF7SW-B2T,
IIF1SW-B5, and IIF4SW-B5 were named after they were sequenced and found to all
belong to the same, previously unidentified species.
The new species, Methylobacterium ajmalii, has been named
after Ajmal Khan, a renowned Indian biodiversity scientist, by a team led by
geneticist Swati Bijlani of the University of Southern California. This new
discovery is also closely related to M. indicum, a previously identified
species.
Two of the team members, Kasthuri Venkateswaran and Nitin
Kumar Singh from NASA's JPL, explained in a press release that isolation of
novel microbes that help promote plant growth under stressful conditions is
necessary to grow plants in severe places where resources are limited.
Given that these microbes can withstand the harsh conditions
on the ISS, the team conducted genetic analysis on the four strains to search
for genes that could be used to aid plant development.
The team writes in their analysis that the whole genome
sequence assembly of these three ISS strains will allow comparative genomic characterization
of ISS isolates with Earth counterparts in future studies.
This will also help with the discovery of genetic
determinants that may be responsible for fostering plant growth in
microgravity, as well as the production of self-sustaining plant crops for
future long-term space missions.
One of the ISS strains, IF7SW-B2T, had promising genes
involved in plant development, including a gene for an enzyme necessary for
cytokinin, which promotes cell division in roots and shoots, according to the
researchers.
There's still a lot of work to be done here; the researchers
admit they've just scratched the surface of the microbial diversity on the
space station. Around 1,000 samples have already been obtained on the
International Space Station, but they are still waiting to be returned to
Earth.
Imagine the fascinating space-faring microbes yet to be
discovered!
The findings were published in the journal Frontiers in Microbiology
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