24 Oct 2018

Microbes in Space

Alli Cartwright, SfAM's ECS Publications Officer looks at the galactic intersection between space travel and microbiology.

For months my Dad has asked me to write a blog on space. The amount of space junk that’s floating around is a regular feature of family discussions.

Stellar rubbish may become less of a worry, as tests are being run to collect the waste with big nets and bring it back to Earth. But what about microbes in space?

The quest to find life on other planets starts with a search for microbes, on the presumption they formed the basis of the evolutionary chain on Earth. In fact, there are even debates on whether life on our planet started somewhere else and was moved to Earth, for example, by an asteroid (Cham & Whiteson 2017).

Looking for life

The search for life on other planets is largely done in three ways; using images, collecting samples and by asking if life is possible, based on measurements of the planet’s atmosphere and surface type.

For example, life on Jupiter, Saturn, Neptune and Uranus is less likely, as these planets are made of frozen gas.

As life started in our waters, H²O is a particularly pertinent feature in the search for space microbes. Images showing the surface of Mars and Venus indicate features associated with water erosion.

Although these pictures show the absence of water on these planets, they may contain water below their surfaces. Recent evidence indicates there’s water below the ice sheets on Mars.

Space oddities

How to test for microbes from other planets? Collect samples. These are then ferried back to Earth upon a multi-billion-dollar shuttle, giving them an intro not even open to royalty.

Upon arrival they’ll potentially visit a microbiology lab within the European Space Agency. The lab in the European Space Agency is equipped with laminar flow benches, incubators and microscopes, ready to detect any ‘space microbe’ which may grow on different agars.

Initially, I was surprised that the quest for space microbes includes agar plates, given the inability of many earthly microbes to grow artificially in labs. As it happens, the relative ease of processing samples, from DNA extraction through to sequencing, means this can be done in space.

The power of Peggy

Last year (2017) the first DNA extractions and sequencing were completed in orbit, aboard the international space station. My first thought when I read about Peggy Whitson, the woman who carried out the microbial analysis was ‘where do I sign up to train with her?’ Unfortunately, she’s since retired.

Dr. Whitson isolated, extracted, amplified and sequenced the cells from two unknown microbes growing in the international space station. At completion of the experiment, the sequences were sent back to Earth for analysis.

The microbes were the bacterium Escherichia coli and the virus Enterobacteria phage lambda. As both are found in the human body, they’re likely to be of astronaut origin. The use of PCR in space means the future is set to allow astronauts to search for microbial life without having to send the samples to Earth.

Having watched too many apocalyptic films where an alien wipes out mankind, this can only be a good thing! Imagine if we incubated an alien virus to which we have no immunity?

Close encounters

If we can now process samples in space to prevent infecting Earth with ‘alien’ microbes, what can be done to protect space from us? The isolation of Peggy’s human-derived ‘space microbes’ proves that we can, and have, introduced microbes to space.

Although the ones Peggy found were probably accidental introductions, humans have also deliberately introduced microbes to space.

At least 49 bacteria, 16 fungi, 5 viruses and 4 yeasts have been tested in space. These have been both human-derived and the extremophile microbes which live in Earth’s harshest conditions.

Guardians of the galaxy

Human-derived microbes are tested in space for a basic understanding of how our bodies would cope if we moved planet. After all, we have 10 bacterial cells to each human cell. It also makes sense to test extremophile microbes in space as they can survive the toughest conditions on our own planet.

These harsh conditions include the icy polar seas or hot hydrothermal vents. Previously these environments were thought to be uninhabitable, but a few microbes and other organisms were able to adapt and utilise these resources relatively competition free.

Cold comfort

Extremophile microbes are the ones I hope never get released onto other planets! Imagine if a polar bacterium is released on Mars. These bacteria can survive a temperature of around -80 ℃.

Without the ability of microbes to adapt and evolve when exposed to extreme environments, we’d have an abundance of sterile regions on Earth. Knowing this, it’s possible one of our microbes could evolve in space.

It’s a relief to learn the European Space Agency cleans and sterilises the equipment prior to departure. Fear that humans could destroy or introduce life to other planets is real and justified.

Imagine if bacteria which has lived in the colder, harsher world of Mars with temperatures between -125 ℃ and 20 ℃ arrived on this planet. Could it multiply uncontrollably in our warmer climate?’

Beyond the lunar

New planets are regularly discovered with only a tiny number within reach for our exploration. As of the 1 August 2018 we knew of 3815 planets in 2853 solar systems, of which we had been able to send machines to only 5 of them!

This means we haven’t even scratched the surface of possible planets where microbes could be living, unaware of our quest to find them.

Alli Cartwright

ECS Communications Officer