Not really space bacteria, but terrestrial bacteria that have been sent into space. This article comes to us via PhysOrg.com, which details research recently published in Applied and Environmental Microbiology, and details some work examining the response of microorganisms exposed to microgravity conditions aboard the Space Shuttle.
Pseudomonas aeruginosa, seen in an electron micrograph to the left, is a Gram negative bacterium that is very prevalent in the environment. The organism is benign in immunocompetent individuals, but is a potent opportunistic pathogen and a significant cause of nosocomial infections. The bacterium is particularly a problem as a cause of broken skin infections, is a primary complication of burn victims, and is the primary cause of death in patients with the genetic disorder cystic fibrosis. One notable and surprising case of Pseudomonas aeruginosa infection was astronaut Fred Haise, who became sick with the bacterium during the Apollo 13 spaceflight in 1970. You may remember him as the astronaut played by Bill Paxton in the very exciting movie about the mission. The case was notable because Mr. Haise was a very healthy individual with no underlying predispositions to disease, but became progressively sicker during the mission. He recovered after the astronauts safely made it back to Earth.
Researchers at Arizona State University were interested in the effects of microgravity on microorganisms, and cultures of P. aeruginosa and Salmonella enteica were sent into Earth orbit as part of the STS-115 space shuttle mission. The scientists examined what genes were turned on and which were turned off as the organism was grown aboard the spacecraft, and correlating those changes with changes in virulence of the organisms. They found that over 167 genes showed altered levels in bacteria grown on the space shuttle in comparison with Earth-bound control organisms, and that the Hfq gene appeared to be a master regulator of space-flight induced changes.
The researchers have hypothesized that the changes that occur during microgravity conditions onboard the spacecraft mimic key conditions that they would encounter during the early stages of infection in the human body, due to the low levels of fluid force on the surfaces of the bacterial cells. In fact, the low gravity conditions onboard the spacecraft actually appear to increase the virulence of these organisms, potentially explaining why Fred Haise became sick with what should have been an innocuous microorganism during the Apollo 13 mission.
BONUS: Based on what we know about the process of disease, what are some other possible reasons that astronaut Fred Haise became sick with this organism in 1970?