Bacterial landlines: contact-dependent signaling in bacterial populations.

Bacterial populations utilize a variety of signaling strategies to exchange information, including the secretion of quorum-sensing molecules and contact-dependent signaling cascades. Although quorum sensing has received the bulk of attention for many years, contact-dependent signaling is forging a niche in the research world with the identification of novel systems and the emergence of more mechanistic data. Contact-dependent signaling is probably a common strategy by which bacteria in close contact, such as within biofilms, can modulate the growth and behavior of both siblings and competitors. Ongoing work with diverse bacterial systems, including Myxococcus xanthus, pathogenic Escherichia coli strains, Bacillus subtilis, and dissimilatory metal-reducing soil bacteria, is providing increasingly detailed insight into the dynamic mechanisms and potential of contact-dependent signaling processes.