During the flight, astronaut Heidemarie M. Stefanyshyn-Piper activated growth of the bacteria in sealed hardware and fixed the cultures after a day of growth to determine changes in gene and protein expression levels.
The bacterial cultures were taken up into space and activated to grow in a separate compartment of the tubes called the growth chamber, said Nickerson. The bacteria didnt have access to the growth chamber until Heide pushed down on a plunger which introduced the bacteria into the growth media. Then they were grown for 24 hours, and at the end of 24 hours, Heide pushed down on the plunger again, which either fixed the bacteria with chemicals that preserved the gene expression message, or else introduced fresh media to keep the bacteria growing to perform the virulence studies.
As a synchronous control experiment back on Earth, Nickersons team grew an identical set of bacteria in the same type of tubes used for flight and incubated them in a special room at the NASA Kennedy Space Center called the orbital environmental simulator. This simulator is linked in real-time to the shuttle, and duplicates the exact temperature, humidity and growth conditions of the shuttle, with the exception that they are not flying in space, said Nickerson. In addition, we were also linked via real-time telecommunications with the shuttle crew when they were activating and terminating our experiments in flight, and we did the exact same things at the same time to the ground samples that the astronauts did to the flight samples thus we had perfectly matched synchronous ground controls.
After the bacteria returned to Earth, the group performed the first global analysis of Salmonella to measure the effect of space flight on gene and protein expression and virulence. By measuring the gene and protein patterns, the researchers could hone in on the key molecular players necessary for virulence from among thousands of poten
|Contact: Joe Caspermeyer|
Arizona State University