(CNN) -- Manned space missions bring with them a
plethora of challenges to keep astronauts alive and
healthy, especially on long-duration space missions.
Astronauts need to breathe, eat, drink, excrete their
food and drink, and be kept free of infections to stay
healthy enough to do their job. The key to an
astronauts' wellbeing has been found, somewhat
contradictorily, to be a group of tiny organisms --
bacteria.
You might think of space as a germ-free
environment, but microbes can be carried to space
inside human gut flora as well as in food and water
and once up there, can be expelled by humans in
their breath.
According to NASA, immune systems weaken during
space flight, making the impact of infection even
greater.
What's more, the greater radiation levels and the
weightless microgravity environment of space alter
bacteria as they grow. Recent work at NASA by Cheryl
Nickerson and her team from Arizona State
University discovered that certain bacteria become
more virulent in space, meaning they become better
at infecting us.
"Salmonella bacteria become more
potent, virulent and are more able to
cause disease," says Nickerson. "They also
become more resistant to factors such as
the acid in your stomach." Nickerson's
group is investigating a range of bacteria
found in food, water and our gut flora,
including Salmonella typhimurium, a
common cause of food poisoning and
diarrhea, and Pseudomonas aeruginosa,
which is a known water contaminant.
'War with microorganisms'
As astronauts spend longer periods of time in space,
their increased exposure to recycled air and water is
likely to affect their risk of infection
Mark Nott is one the people in charge of crew health
at NASA and focuses on keeping microbes at bay.
"We're at a constant war with microorganisms
because they adapt," he says. "The stressful
environment of spaceflight affects them and under
stress your immune system also functions less
effectively and we have to take precautions for this."
Reduced immunity can cause some bacteria, such as
Pseudomonas aeruginosa, to cause illness despite
normally being carried by many of us with no effect.
"However, not all microorganisms are bad and so the
key is to understand how they change and impact us,"
explains Nott, who also found that the infectious
bacteria Staphylococcus aureus, which causes a range
of symptoms from boils to food poisoning, becomes
benign in microgravity.
By understanding the changes in salmonella and
other disease-causing bacteria in microgravity
Nickerson hopes to not only keep crew healthy but
also help humans down on Earth through the
development of drugs and vaccines.
"Infections are becoming harder to treat; we have no
vaccine for salmonella food poisoning and it remains
[one of] the leading cause of bacterial food-borne
illness worldwide," states Nickerson.
Spaceflight opens up a new world of research that
can't take place on Earth and Nickerson has unmasked
key changes in the behaviour of genes in the bacteria
which aren't usually seen under gravity. "Vaccines are
about identifying targets and in microgravity the
bacteria have unmasked themselves and revealed
secrets to help develop therapeutics."
Sustaining life in space
The research is in its early stages but it's
just one example of how bacteria are
being investigated by space agencies. Far
from just a health hazard, bacteria could
be used to help sustain astronauts in
space, as a source of food and oxygen.
"The major advantage to using bacteria is
the size of them," explains Christophe
Lasseur, coordinator of life support
research and development at the
European Space Agency (ESA). "For space
missions the mass of oxygen, food, and
water is high and not compatible with
current launch technologies. A crew of six
to Mars would need over 30 tons."
Lasseur directs the MELLiSSA programme at ESA,
which aims to develop a regenerative life-support
ecosystem for use on board spacecraft. "We need to
recycle everything for an ecosystem that can sustain
human life," says Lasseur. The team wants to recycle
80% of all mass on board, including carbon dioxide,
which can become toxic if allowed to build up.
Key algae and bacteria can mop up carbon dioxide
and in turn release oxygen to enable astronauts to
breathe. "We have approached this molecule by
molecule, first oxygen, then water and now food,
which is more complex," says Lasseur.
The chosen range of bacteria not only utilize carbon
dioxide but can also harness other human waste
products, such as urine and feces -- a win-win given
their growth results in food for the astronauts.
Eating bacteria grown on urine may not sound like a
delicacy, and it isn't, which is why psychology also
comes into play. "Our most advanced work is using
spirulina as this has been used as a protein source for
many centuries and in many countries, making it
much more psychologically acceptable," explains
Lasseur. Spirulina is a cyanobacterium found in many
salt water lakes and is consumed readily by lake
communities. The edible bacterium is also marketed
as a health supplement.
In the search for bacteria that feed on our food
waste, Lasseur's team discovered a hidden gem that
has an additional medical benefit -- helping to fight
cholesterol.
"We were looking for bacteria which use a lot of
carbon and nitrogen as there's a lot of this in waste
disposal," states Lasseur. The resulting use of
Rhodospirillum rubrum led to a nutritious product
found to produce significantly lower levels of
cholesterol in mice and will soon be marketed by
spin-off company EzCOL BV, which is in talks with big
pharma. This bacterium has been by-passed in favor
of more nutritious alternatives for consumption by
astronauts but the research to get there has borne
beneficial fruit for those of us not venturing up into
space.
As for the astronauts, Mars missions could be a
reality in the, albeit distant, future. And when the
day comes, crews could depart feeling confident of
reaching the red planet well fed, watered and free of
infection.
Source: cnn.com