A Rapid Fluorescence-Based Screen to Identify Regulators and Components of Interbacterial Competition Mechanisms in Bacteria.

Contact-dependent antibacterial mechanisms enhance bacterial fitness as they enable bacteria to outcompete their rivals and thrive in diverse environments. Such systems also allow pathogenic bacteria to establish a niche inside a host, where they must compete with commensal microflora. In many cases, antibacterial systems are tightly regulated by complex sensor and signal transduction networks. Deciphering these regulatory networks, as well as identifying functional components of antibacterial mechanisms, are valuable objectives since essential regulators and components present possible targets for developing antivirulence therapies. Here we describe Bacterial Competition Fluorescence (BaCoF), a methodology that relies on a fluorescence signal to determine the outcome of bacterial competitions. This methodology enables screening of mutant libraries to identify genes that are essential for activating a contact-dependent antibacterial system of interest. Thus, this methodology can be applied to reveal essential regulators and components of antibacterial systems in bacterial pathogens.