There's more to learn about the viruses that infect bacteria over at Discover. This time, it's Ed Yong talking about the bits of DNA that can be leftover in bacterial genomes from viral infections, and how they might actually be helping their hosts:
These captives are called cryptic prophages and they can make up a fifth of a bacterium's DNA. Their existence is puzzling. Bacteria are known for having small, streamlined genomes, yet in they have foreign and potentially harmful viral DNA loitering among their genes. Why?
To find out, Xiaoxue Wang from Texas A&M University found all nine cryptic prophages from the common bacterium Escherichia coli and, with care and precision, snipped them all out. And to his surprise, the bacteria were the worse for it.
Biology is so damned complicated... awesome.
Note: I meant to post this last week when I read Ed's piece, but due to the vagaries of Movable type, it didn't get posted. But go look - it's still there :-P