Alternative Actions for Antibiotics

Compounds recognized as having antibiotic functions may have other possible roles in microbial interactions. Microbes generate signals, which coordinate mutually beneficial activities ( 1 ). They also produce antibiotics that kill prey, suppress competitors, or deter predators ( 2 ). Recent observations have led to the view that antibiotics often act as mutually beneficial signals ( 3 – 6 ). Exposure to sublethal concentrations of antibiotics can indeed alter microbial metabolism and even change behavior in beneficial ways, triggering reactions such as fleeing or hiding within the protective environment of a microbial aggregate (biofilm). But the weapon-signal dichotomy of functions for these compounds is a false one—there may be other possible information-related actions of naturally produced antibiotics: cues and manipulation.