(This video is no longer available for streaming.) Bonnie Bassler has been called the "Bacteria Whisperer," and even if she doesn't speak directly to microbes, she is passionate about them. Until recently, no one thought bacteria communicated with one another and coordinated their behavior. But Bassler, a molecular biologist at Princeton, has discovered "quorum sensing." In some cases, when certain bacteria sense that they are in a large enough group (a quorum), they mobilize to attack a host, triggering disease. The implications for medical science are huge.