Bacteria are often pictured as lone cells moving randomly about. In fact, millions of bacteria frequently stick together in well-organized colonies. This is slime-or, as microbiologists prefer to call it, "biofilm." A research team at the Center for Biofilm Engineering at Montana State University (MSU) in Bozeman has now identified the chemical signal secreted by bacteria that tells the microbes when to form-and when to desert-these bacterial structures.

Select from the choices above to read the entire article.