( > Scientists have learned that bacter...)To control germs, scientists deploy tiny agents provocateurs

Scientists have learned that bacteria sense each other and the overall density of their colony by continuously exchanging small molecules and peptides - a process known as quorum sensing. Past a certain density threshold, the colonies unite to initiate group behaviors, such as biofilm formation.

Attempting to manipulate quorum sensing in both plant and animal bacteria, Blackwell and her team are designing new compounds that mimic acylated homoserine lactones (AHLs), a natural molecule that is used by more than 50 species of bacteria to "talk." Researchers have so far studied around 15 variations of AHLs. In particular, the UW chemists are synthesizing molecules that interact with a specific class of proteins that are linked to AHLs and are critical in quorum sensing.

"We want to design molecules to confuse bacteria so they can't sense their neighbors," says Blackwell, "but some types of quorum sensing are beneficial, so we are simultaneously searching for compounds that selectively turn on group behaviors."

Using new combinatorial chemistry techniques, Blackwell and her team are screening through hundreds of molecules at a time. The researchers have so far unveiled three promising organic compounds that seemingly quell bacterial signaling.