Microorganisms, or microbes, are among the oldest known inhabitants on Earth. They have survived the ravages of time, the tests of evolution, and are constantly adapting to suit inhospitable conditions, while contributing to the planet’s overall environment.
Even as new larger organisms take birth on Earth, evolve and become extinct, microbes survive. The question then arises, can such minute, yet tough organisms survive in conditions beyond Earth?
One of the earliest experiments observing microbial ability to persist in space environments involved a Russian satellite carrying strains of E. coli and Staphylococcus to space, in 1960. The study proved the survivability of these microbes in microgravity. In later years, NASA’s experiments also concluded that not only did some microbes survive hostile space conditions, but also thrived in them. For instance, bacterium Deinococcus radiodurans survived, despite being zapped with intense gamma radiation and exposed to oscillating temperatures at specific intervals, all in the vacuum of space. But can humans safely share space with microbes, especially when sealed in an enclosed zero-gravity environment like a space station? A constant human presence in the International Space Station (ISS), orbiting the Earth at an altitude of ~400 km, with all its essential functions, including living, eating, washing, and working spaces for crew, creates a hotbed for microbial life.
“The ISS harbours a diverse array of microbes, including bacterial and fungal phyla, viz. Acintobacteria, Firmicutes, Proteobacteria, Ascomycota and Basidiomycota,” the American Society for Microbiology (ASM) informs.
How did they get there?
Biologists suggest that some microbes inevitably ride on crew members and cargo to the space station, and it is imperative to identify and control those that may be harmful.
A hermetically sealed system, the ISS is subjected to microgravity, radiation, elevated carbon dioxide levels, and recirculation of air through HEPA (high-efficiency particulate air) filters and is considered an extreme environment – a playground for microbes, where they not only survive, but multiply. And each time a new crew arrives, newer microbes hitch a ride. Multiple investigations have tracked and analysed the station’s tiniest residents to protect crew members and equipment, and even other planets, from potential threats.
The human body contains 10X the microbes than human cells, and bacteria and fungi grow in and on just about everything on Earth. The human body is an excellent host for microorganisms too.
“Most bacteria are harmless, and many are beneficial or even essential to human functioning and wellbeing. But microgravity can make some microbes more likely to cause disease and bacteria and fungi may affect the functioning of spacecraft systems, such as corroding metal. These organisms could also contaminate other planetary bodies that spacecraft and humans land on,” informs NASA.
“Experimentation shows that several microbes are associated with the microbiome of astronauts, while some are opportunistic pathogens. While scientists are happy to observe that these microbes can exist in microgravity conditions aboard the ISS, there is genuine concern about contamination, and devising procedures to disinfect the spacecraft and protect astronauts from disease in space,” the ASM echoes.
Meanwhile, NASA has sent several microbes to space, including on the Apollo 16 and 17 missions, with astonishing results. Microbes, including E. coli and Staphylococcus demonstrated increased resistance to antibiotics in space.
While responses to space stressors varied between microbes, the bacteria seemed to be evolving strategies to survive and replicate in space. Scientists also demonstrated that much like on Earth, changes in a microbe’s physical environment triggered it to switch on appropriate genes to compensate for the changes.
1960
A Russian satellite carrying strains of E. coli and Staphylococcus to space, for the first time
ISS Boeing Antimicrobial Coating
It tests surface coatings designed to inhibit the growth of microbes to protect crew members and equipment on a spacecraft
Keeping an eye on microbes
Microbial Observatory-1 - One of the first investigations to monitor microbes present on the space station, including some that may act as pathogens and cause disease
Microbial Tracking-2 - An investigation cataloguing and characterising microbes, with disease-causing potential, on the space station
BioRisk-MSV - A long-running Roscosmos investigation, examining physical and genetic changes in bacteria and fungi on interior and exterior surfaces of the space station
TEST investigation from Roscomos - It examined samples from the exterior surface of the space station and in life support systems
NASA’s ISS External Microorganisms - It collects samples near life support system vents outside the station to examine whether the spacecraft releases microorganisms
Myco - A JAXA (Japan Aerospace Exploration Agency) investigation, evaluating whether fungi inhaled by crew members or that adhere to their skin, can act as allergens
Microbe-I, Microbe-III, and Microbe-IV - These monitor the abundance and diversity of fungi and bacteria in Kibo, the ISS’ Japanese experiment module
(Source: NASA)