The roles of microbes in space from a health perspective

The survivability tests of microbes in space conditions started more than 90 years ago. The early experiments utilised balloon flights and rocket payloads to expose the microorganisms in spaceflight conditions. In 1966, the National Aeronautics and Space Administration (NASA) performed experiments on microbes by exposing them to space conditions. The resilience of those organisms was poor due to the radiation of the space.

Since then, the initiation of the International Space Station (ISS) expeditions in 2000 in Low Earth Orbital (LEO) has enhanced the scope of advanced research on microbes. The closed system in ISS acted as a microbial testing facility in the past to conduct research on microbial adaptation and resilience to space conditions. Microorganisms must acclimate primarily to radiation and microgravity to survive in space. This adaptation can be beneficial or harmful for the crew members and spacecraft. Besides, NASA's plan to return humans to the lunar surface and Mars by 2033 enhances the requirement to understand the roles of microbes in space from the health point of view.

Exploiting and engineering microbes essential for human health can be utilised to address limited resources and potential health risks for deep space exploration. This self-sufficiency can be achieved by implementing bio-regenerative life support systems (BLSS). Microbes, primarily microalgae, play significant roles in BLSS by providing oxygen, fatty acids, minerals, proteins, carbohydrates, and vitamins for a balanced diet.

The presence of microorganisms with enhanced virulence in space missions could increase the risk of crew members contracting infections. Bacterial infections are generally treated with antibiotics, but the formation of biofilms and propagation of multi-drug resistance microbes in spaceflight environments limit these therapeutic options.

Additionally, antibiotic-associated diarrhoea may arise in space as a side effect of administering antibiotics to treat infections. Engineered microorganisms can be a promising alternative to overcome serious health issues in space. Engineered yeast probiotics reduce inflammation in IBD by reducing the extracellular adenosine triphosphate (eATP) by secreting the eATP-degrading enzyme.

Besides, factors like increased bone decalcification in space may cause kidney stone diseases. Engineered bacteria can produce oxalate decarboxylase enzyme, which has shown efficacy in breaking down oxalate in kidney stones.

Moreover, the gut microbiome can affect general physiological responses, immunity, and health. Genetically modified microorganisms alter the microbiome's composition and inhibit opportunistic pathogens' growth.

Our understanding of microbial life in space has come miles, from early balloon tests to the ISS lab. Maintaining a healthy astronaut microbiome and harnessing the power of engineered microbes will be vital for future deep space exploration. The imminent of space travel may be tiny, but its impact could be gigantic.

Sabbir Rahman Shuvo, PhD is an Assistant Professor at the Department of Biochemistry & Microbiology at North South University, Dhaka. E-mail: sabbir.shuvo@northsouth.edu