Saturday, April 28, 2012

More stuff that happen differently in space!

☞ Bacteria grow more…and grow more deadly.

Thirty years of experiments have shown that bacterial colonies grow much faster in space. Astro-E. coli colonies, for example, grow almost twice as fast as their Earth-bound counterparts. Furthermore, some bacteria grow deadlier. A controlled experiment in 2007 testing salmonella growth on the space shuttle Atlantis showed that the space environment changed the expression of 167 of the bacteria's genes. Studies performed after the flight found that these genetic tweaks made the salmonella almost three times more likely to cause disease in mice than control bacteria grown on Earth.

There are several hypotheses as to why bacteria thrive in weightlessness. They may simply have more room to grow than they do on Earth, where they tend to clump together at the bottom of petri dishes . As for the changes in gene expression in salmonella, scientists think they may result from a stress response in a protein called Hfq, which plays a role in controlling gene expression. Microgravity imposes mechanical stresses on bacterial cells by changing the way liquids move over their surfaces. Hfq responds by entering a type of "survival mode" in which it makes the cells more virulent.

By learning how salmonella responds to stress in space, scientists hope to learn how it might handle stressful situations on Earth. Hfq may undergo a similar stress response, for example, when salmonella is under attack by a person's immune system.