Bacterial Growth Affected By Gravity
On Earth or in space, microbial communities will undoubtedly follow their human counterparts. In two NASA-funded studies, the bacteria known as Pseudonomas aeruginosa, an opportunistic human pathogen, was cultured both on earth and aboard shuttle Atlantis in 2010 and 2011. The goal was to see if the bacteria behaved differently due to microgravity.
One of NASA’s primary goals is to minimize health risks associated with extended spaceflights. By studying how bacterial communities grow in space, researchers may be able to eliminate potential hazards associated with microbial growth.
Bacteria often attach to surfaces, creating communities known as biofilms. Some biofilms can threaten human health and safety with their increased resistance to the immune’s systems defenses or treatment with antibiotics. Additionally, they are capable of damaging spacecraft equipment, such as water purification systems, and can corrode surfaces or clog air filters. Therefore, elimination of the risks that biofilms pose to the astronauts and crew is of utmost importance for long-term spaceflight missions.
In 2010 and 2011, astronauts aboard space shuttle Atlantis and scientists on Earth performed parallel experiments, culturing samples of P. aeruginosa bacteria using conditions that encouraged biofilm formation. According to Cynthia Collins, Ph.D., principal investigator for the study, "artificial urine was chosen as a growth medium because it is a physiologically relevant environmental for the study of biofilms formed both inside and outside the human body."
Upon their return to Earth, researchers observed a unique, previously unseen structure formed by the bacteria cultured in space. The biofilms contained more cells, more mass, and were thicker than the control biofilms grown on Earth. Microscopy images showed a dense mat-like "canopy" structure supported above by the membrane "columns". Unlike the spaceflight biofilm, Earth-grown biofilms were uniformly dense, flat structures. These results provide the first evidence that spaceflight affects community-level behavior of bacteria.
Such findings open doors to new research that could offer new ways to reduce the spread of infections. According to Collins, "Beyond its importance for astronauts and future space explorers, this research could also lead to novel methods for preventing and treating human diseases on Earth. Examining the effects of spaceflight on biofilm formation can provide new insights into how different factors, such as gravity, fluid dynamics, and nutrient availability affect biofilm formation on Earth."
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Space shuttle image via Shutterstock.