The medium is the message: Manipulating salmonella in spaceflight curtails infe...( Infectious pathogens like Salmonell...)

Infectious pathogens like Salmonella typhimurium employ a startling array of techniques to skillfully outwit the body's defense mechanisms and produce illness. Through their expression of genesthe fundamental building blocks of cellular physiologysuch microbes ingeniously adapt to varied environments, modifying their disease-causing potential or virulence.

Although the study of a broad range of microbial virulence factors is now well advanced, many pieces of the puzzle are still missing. Cheryl Nickerson, a researcher at Arizona State University's Biodesign Institute, has explored the novel environment of space to investigate the cellular and molecular machinery of virulence. There, the space shuttle crew grow the bacteria in triple-enclosed containers under conditions of minimized gravity (or microgravity). Nickerson's spaceflight experiments have shown that Salmonella gene expression and virulence are profoundly altered by microgravity, with the pathogenic cells undergoing a significant increase in their infectious disease potential.

Nickerson's latest findings, published in the journal PLoS ONE, are derived from experiments aboard NASA space shuttle mission STS-123, launched in March, 2008. This research validated results and broadened the scope of spaceflight experiments from STS-115, conducted two years earlier.

In addition to confirming the effects of microgravity observed in the STS-115 experiments (known as MICROBE), the new study homed in on the importance of the microbial growth medium to gene expression and virulence during spaceflight. "Pathogenic cells are smart," Nickerson stresses, pointing to their remarkable ability to fine-tune virulence factors in response to subtle environmental cues.

S. typhimurium, Nickerson's pathogen of choice, is a rod-shaped, motile bacterium and occasional unwelcome visitor to the human gastrointestinal tract, where it is a leading cause of food poisoni
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