Humans have always been captivated by the vast expanse of space and the mysteries it holds. As we aspire to travel further into the cosmos, the challenges we face are not only those regarding isolation or reaching light speed, but much more down-to-earth factors. While purée packet space food has evolved and may suffice for short space travel, further advancements such as growing food will likely be necessary for extended deep space travel (Gohd, 2021). Despite these needs, growing food in space is not feasible as plants depend on “helpful” bacteria in soil that is exclusive to the Earth (Gohd, 2021).
Plot twist, the International Space Station (ISS) may have a solution for this. After two decades of serving astronauts, the ISS has recently been discovered to serve as a habitat for microbes. While the ISS is a very clean place for reasons such as safety and experiments, it is not a sterile environment as astronauts are constantly arriving and departing this space hub. Therefore, it’s not that surprising that the ISS hosts three new strains of bacteria, as an average human carries around 100 trillion microscopic organisms (Gohd, 2021).
Harsh space conditions such as microgravity, cosmic radiation and extremes of temperature, expose the bacteria to the conditions of Earth pre-life, allowing adaptation and evolution (Bijlani et al., 2021). These three strains of bacteria found on the ISS hold promise for supporting plant growth and in such extreme environments like space they may be crucial for extended space missions in the future.
The three strains, initially designated IF7SW-B2T, IIF1SW-B5 and IIF4SW-B5, were then classified as Methylobacterium ajmalii sp. nov., in tribute to the late Indian biodiversity scientist Muhammad Ajmal Khan, who passed away in 2019 (Bijlani et al., 2021). Figure 1 is a transmission electron micrograph of genus Methylobacterium, species S2R03-9T Methylobacterium jeotgali, which is a relative of the new strains discovered on the ISS (Aslam et al., 2007).
The Methylobacterium genus is known to promote plant growth and biocontrol activity against pathogens, while assisting in nitrogen fixation and phosphate solubilization, which are needed processes for plants (Gorey, 2021).
Nitrogen fixation is a crucial process in which atmospheric nitrogen (N2) is converted by bacteria, such as Methylobacterium, to ammonia (NH3+), a usable form for plants; this can be observed in figure 2.
Additionally, phosphate solubilization is where certain bacteria convert insoluble forms of phosphate in soil to soluble forms for accessible plant uptake and efficient plant absorption.
Through the exploration of the roles of these strains in waste decomposition, essential nutrient production and pathogen resistance, they become pivotal for the sustainability and longevity of human space missions. The Methylobacterium ajmalii novel species have the potential to transform celestial objects into sustainable ecosystems, providing astronauts with essential resources for exploration and even colonization. Looking further ahead, they could even pave the way for long-term human development beyond Earth.
References
Gohd, C., 2021. Newly discovered bacteria on space station could help astronauts grow plants on Mars. [online] SPACE.com. Available at: <https://www.space.com/space-station-bacteria-discovery-grow-food-on-mars> [Accessed 19 September 2023].
Bijlani, S., Singh, N.K., Eedara, V.V.R., Podile, A.R., Mason, C.E., Wang, C.C.C. and Venkateswaran, K., 2021. Methylobacterium ajmalii sp. nov., Isolated From the International Space Station. Frontiers in Microbiology, [online] 12(2021). https://doi.org/10.3389/fmicb.2021.639396.
Image References
Aslam, Z., Lee, C.S., Kim, K.-H., Im, W.-T., Ten, L.N. and Lee, S.-T., 2007. Methylobacterium jeotgali sp. nov., a non-pigmented, facultatively methylotrophic bacterium isolated from jeotgal, a traditional Korean fermented seafood. International Journal of Systematic and Evolutionary Microbiology, 57(3), pp.566–571. https://doi.org/10.1099/ijs.0.64625-0.
Cornell, B. 2016. Bioninja. Available at: <https://old-ib.bioninja.com.au/options/option-c-ecology-and-conser/c6-nitrogen-and-phosphorus/nitrogen-cycle.html> [Accessed 19 September 2023]