Bacteria become more virulent in a space shuttle?

Will bacteria become more dangerous if they travel in the space in a “weightless” environment?
Why would bacteria travel to space to start with? Obviously it could only happen in a space shuttle!

I found this story on the BBC web site

“Wherever humans go, microbes go; you can’t sterilise humans. Wherever we go, under the oceans or orbiting the Earth, the microbes go with us, and it’s important that we understand… how they’re going to change,” Cheryl Nickerson, from the Center for Infectious Diseases and Vaccinology at Arizona State University, US, told the Associated Press.

• Read the full story here
• Read an older scientific article explaining this finding in the Proceedings of the National Academy of Science (for advanced readers only!)
• An older story about “bacteria on the moon”