Abstract
Over the last 15 years, it has become increasingly apparent that a single class of compounds, the acylated homoserine lactones (AHLs), elicit effects on many levels of biological and ecological organization. Despite the fact that the distribution of AHL production in the prokaryotic phylogenetic tree is restricted to a small set of genera, representatives of these genera are abundant in the environment and are responsible for processes of much interest to humans. As well as driving interactions between clones, AHLs have been shown to mediate interactions between different species of bacteria and between bacteria and higher organisms, either through the phenotypes they regulate or directly through their own chemical behaviour. Understanding the biological activity of AHLs and the ecological consequences of these activities may provide us with an opportunity to manipulate the composition and function of complex biological assemblages. Ultimately, this broadens the biotechnological focus of AHL-based research beyond the attenuation of virulence in humans and plant pathogens.