Plants Growing in Space are at Risk from Bacterial Infections

I have spent the last few years thinking, perhaps assuming that astronauts live off dried food, prepackaged and sent from Earth. There certainly is an element of that but travellers to the International Space Station have over recent years been able to feast on fresh salad grown in special units on board. Unfortunately, recent research suggests that pathogenic bacteria and fungi can contaminate the ‘greens’ even in space.

It’s been at least three years that astronauts have been able to eat fresh lettuce and other leafy items along with tortillas and powdered coffee.. Specially designed chambers on board allow them to grown plants under carefully controlled temperature, water and lights to ensure a successful harvest.  There is however an issue that the ISS is a relatively closed environment and so it is easy for bacteria and fungi to spread and astronauts to get ill. 

International Space Station
The International Space Station stretches out in an image captured by astronauts aboard the SpaceX Crew Dragon Endeavour during a fly-around in November 2021. Credit: NASA

A paper just published in Scientific Reports and NPJ Microgravity and authored by a team led by Noah Totsline explores what happens with lettuce grown under ‘simulated’ weightless environments (the device known as a clinostat rotate them so that plants did not know which way was up or down). This was achieved by being gently rotated. Plants it seems though, are pretty good at sensing gravity using their roots. The team found that plants under these conditions were more prone to infection than those on Earth in particular Salmonella.

One of the main lines of defence for plants is their stomata. These are tiny pores in the leaves, much like the pores in our skin, that close to defend when an environmental stress is detected, such as bacteria.  The team exposed plants in their micro-gravitational environment to find the plants opened the stomata instead of closing them. 

The team went a step further and introduced a natural bacteria known as UD1022 which usually helps to protect plants. In the clinostat however, it failed to help the plant to protect itself from other more harmful bacteria.

The research was not just an interesting scientific problem but does solve real world problems. Space is slowly opening up with more and more non-astronauts becoming astronauts and travelling into space and this is only going to increase. As SpaceX and the like press ahead with the commercialisation of space travel we absolutely must find a way to grow and farm sustainable and healthy food instead of prepackaged snacks if we are to become a truly space fairing civilisation. 

We are some way away from that of course but this is step one in a long journey. Sadly it is not as simple a task as sterilising the seeds since their could easily be microbes in the environment on board the ISS (or other space craft that come in the future) and perhaps it is these that pose the greatest risk. The team are now looking at ways to genetically modify plants to help them cope in the microgravity of space.