Microbes are organisms that can only be seen under a microscope. They include viruses, bacteria, protozoa, unicellular algae, fungi and mites. And to grow microbes in a petri dish is a very simple thing. Just rub practically anything, clean an agar plate, let it sit for a few days in a warm room and that’s it.
However, the microbial species that are possible to be grown in a petri dish are just a tiny fraction of the bacteria and other microorganisms that would be collected by the swab.
The collection of bacterial and fungal species that live among us is growing. And this growth is no exception in low-gravity environments, such as the International Space Station (ISS).
Researchers from the United States and India who work closely with NASA and discovered four strains of bacteria that live in different places on the ISS. Of these four, three were, until now, totally unknown to science.
These three were isolated in 2015 and 2016. One of them was found on the top panel of ISS research stations. The second was in the dome, and the third was found on the surface of the dining table. The fourth was in an old HEPA filter that returned to Earth in 2011.
All four strains are from a family of bacteria found in soil and fresh water. They are involved in nitrogen fixation, plant growth and can also help prevent plant pathogens. All of which shows that they are good bacteria to have around if you are growing things.
But what were they doing at the top of the ISS? They were there because the astronauts who live on the ISS have been growing small amounts of food for years. Because of this, it is not surprising that plant-related microbes were found.
One of the strains found, that of the HEPA filter, was identified with a species known as Methylorubrum rhodesianum. And the other three were sequenced and belong to the same species that had not been previously identified. Therefore, the strains were called IF7SW-B2T, IIF1SW-B5 and IIF4SW-B5.
The team, which was led by geneticist Swati Bijlani from the University of Southern California, proposed that the new species be called Methylobacterium ajmalii in honor of Ajmal Khan, who is a well-known Indian biodiversity scientist.
“To grow plants in extreme places where resources are minimal, isolation of new microbes that help promote plant growth in stressful conditions is essential,” explained two team members, Kasthuri Venkateswaran and Nitin Kumar Singh of NASA’s JPL.
The researchers found that one of the strains, IF7SW-B2T, had promising genes involved in plant growth. Including a gene for an enzyme essential for cytokinin, which promotes cell division in roots and shoots.
Of course, there is still much more research to be done. And the researchers acknowledge that they haven’t even scratched the surface of the microbial diversity that exists on the ISS. Approximately one thousand samples have already been collected on the ISS. But they are still waiting for a trip back to Earth.