Scientists have known that wherever humans go, we carry microorganisms with us, and the International Space Station is no exception. Several types of non-pathogenic bacteria and fungi have been found there in recent studies that have looked for the presence of microbes on the ISS. Some of that bacteria is thought to come from Earth during the assembly of various parts of the ISS. Now researchers have discovered three novel strains of bacteria that have been found on two consecutive ISS trips. The microbes are from the Methylobacteriaceae family, and they could help scientists learn more about how to promote plant growth in space. The findings have been reported in Frontiers in Microbiology.
Methylobacteria are good for plants; they play roles in stress tolerance in sterile environments, nitrogen fixation, the promotion of plant growth, phosphate solubilization, and protection against plant pathogens. One strain that was found in this study is known: Methylorubrum rhodesianum. Three others are novel, rod-shaped, motile bacteria. A genetic analysis showed they're related to Methylobacterium indicum. They are now designated IF7SW-B2T, IIF1SW-B5, and IIF4SW-B5, and a proposed name is Methylobacterium ajmalii for Indian biodiversity scientist Dr. Ajmal Khan.
There are very few resources for plants to draw on in space, so it will be critical to know as much as we can about what plants need to grow there as humans spend more time on missions and explore the idea of going to Mars. More work will be needed, but microbes like these may be critical for plants to grow in those stressful environments. Beneficial microbes may be a good addition to the ISS. But the researchers also noted that crew safety is the first priority, so it's important to have a good understanding of how plant pathogens might interact with humans in an environment like the ISS.
For the last six years, monitoring for bacterial growth has been happening at eight places on the ISS, like the plant growth chamber, and the location where experiments are conducted. Although hundreds of these samples have been assessed, there are many more that were gathered from other sites on the ISS that are still awaiting a ride back to earth where they can be analyzed.
The study authors are hopeful that eventually, there will be molecular biology equipment onboard the space station that will be able to perform the analysis.