2015 Elsevier Inc. All rights reserved. It is now well recognized that most bacteria produce signals that allow communication between cells by emitting specific chemical signals. This cell-cell communication can be within a single population of bacteria (intraspecies signaling), between bacterial populations (interspecies signaling) or between bacteria and other organisms (interkingdom signaling). This chapter discusses the current understanding of bacterial signaling using examples of communication systems including: signaling in Gram-negative bacteria via quorum sensing with N-acyl homoserine lactones; signaling in Gram-positive bacteria via ?-butyryl lactones and small peptide signals; and signaling via Autoinducer-2 and -3, and bacterial neuropeptides. In addition are covered: bacterial eavesdropping; bacterial signal interference; and interkingdom signaling. 2015 Copyright
