Bacteria are constantly evolving to survive. One major consequence is that many harmful microbes are becoming resistant to antibiotics and disinfectants, creating serious challenges for medicine and public health. But not all bacteria are dangerous. In fact, many are essential to keeping the human body healthy. Now, scientists are exploring whether it may be possible to influence bacterial behavior instead of simply trying to destroy bacteria outright.

Inside the human mouth, bacteria are in near constant communication. Roughly 700 bacterial species live there, and many exchange chemical messages through a process called quorum sensing.…