In the last two decades, there has been a growing interest in bacteria and other  microorganisms. This research has provided interested insights into the nature of life (Parke, 2013), cooperation (Lyon, 2007), individuality (Clarke, 2016), species (Franklin, 2007) and other issues in philosophy of science (O’Malley, 2014). In this talk, I will focus on the capacity of some bacteria to produce molecules that are usually classified as ‘signals’ and I would like to defend two claims. First of all, I will argue that in this context expressions such as ‘signalling’ should be taken at face value and that certain interactions between bacteria actually qualify as genuine forms of communication. The second goal is to use this case study to revise our general theories of signalling. In particular, I will argue that there are some aspects of bacterial signalling that do not fit the standard model; some features that usually included in the definition of communication are probably not necessary (e.g. response flexibility) and others that are not included are crucial (e.g. being a minimal cause). Finally, I will discuss the relationship between my proposal and other accounts, such as the ‘influence’ approach and the Organizational Approach to Biological Communication (Frick, Bich and Moreno, 2019).