Microbes in Space?!
With hand sanitizer and bacterial wipes that guarantee 99.9% bacterial kill, it is evident that the world is aware of the trillions of microbes that surround us. Although some microbes serve a good purpose, such as those within probiotics or more specifically the E. coli within our large intestine, many of the ones that are known by the public are associated with deadly infections and diseases. Yet, what if I told you that more lethal species of microbes exist somewhere else? You might be thinking another continent, biome, or perhaps an unexplored region of the Earth, but I am thinking beyond our atmosphere.
Research has demonstrated that microbes are more lethal and develop further resistance when exposed to microgravity. In a research paper that sought to determine the effects of microgravity on microbial growth and metabolism, researchers tested how antibiotics would affect specific species’ production of metabolites when placed in spaceflight. A majority of the microbes tested displayed an increase in the production of secondary metabolites when placed under microgravity. To name one Streptomyces plicatus produced more Actinomycin D, an antibiotic commonly used in chemotherapy that prevents the elongation of an RNA chain by binding to the DNA transcription initiation complex (Huang et al.). The increased production of secondary metabolites doesn’t necessarily stimulate further growth, but can inhibit the growth of competing species, thus providing microbes with a selective advantage.
Furthermore, it has been shown that spaceflight promotes biofilm production in specific microbes. In a study that focused on the biofilm production of Pseudomonas aeruginosa, researchers discovered that in spaceflight, P. aeruginosa demonstrated increased cell number in biofilms, biomass, and mean thickness. More surprisingly, unlike biofilms produced under normal gravity conditions, the biofilms created in space “were column-like structures with a significant amount of unoccupied space.” Researchers associated this change in shape with flagella-driven motility after comparing the biofilms produced by wild-type P. aeruginosa (column-like) and mutant P. aeruginosa with deficient flagella-driven motility (mat-like). Knowing that flagella-driven motility plays a key role in biofilm formation under hydrodynamic environments, it made sense that they had some sort of role in biofilm development when P. aeruginosa was placed under a static environment (i.e. spaceflight) (Kim et al.). The development of biofilms by P. aeruginosa demonstrates that microbes are able to adjust to extra-terrestrial environments, which necessitates further studies about microbial life when placed under low-gravity surroundings.
With all in mind, as we desire to find a way to send astronauts to Mars, it is also important that current and future microbiologists look towards researching the metabolism, growth, and resistance of microbial species in extra-terrestrial environments. Increased production of secondary metabolites in microbes when placed under microgravity provides microbes with a selective advantage against competing species. Who is not to say that such microbes will learn to develop a selective advantage against common classes of antibiotics such as beta-lactams, macrolides, and fluoroquinolones to name a few. Moreover, biofilm production by microbial species have been shown to not only confer resistance but also increase their pathogenicity. This is important to note as species such as P. aeruginosa are associated with causing urinary tract infections, and when alongside Candida albicans, can cause some respiratory tract infections.
While current microbiologists seek to find a solution to the growing issue of antimicrobial resistance taking place on Earth, perhaps its time for the aspiring microbiologists initiate microbiological research for the microbes that happen to go beyond our atmosphere.
