Biological nanofactories, which are engineered to contain modules that can target, sense and synthesize molecules, can trigger communication between different bacterial populations. These communications influence biofilm formation(1,2), virulence(3,4), bioluminescence(5,6) and many other bacterial functions(7,8) in a process called quorum sensing(9). Here, we show the assembly of a nanofactory that can trigger a bacterial quorum sensing response in the absence of native quorum molecules. The nanofactory comprises an antibody (for targeting) and a fusion protein that produces quorum molecules when bound to the targeted bacterium. Our nanofactory selectively targets the appropriate bacteria and triggers a quorum sensing response when added to two populations of bacteria. The nanofactories also trigger communication between two bacterial populations that are otherwise non-communicating. We envision the use of these nanofactories in generating new antimicrobial treatments that target the communication networks of bacteria rather than their viability.