Tiny Conspiracies

The secret, social lives of bacteria

The explosion of research in quorum sensing, especially in pathogenic bacteria, is pointing the way to new biotechnological applications. If therapies could be developed that manipulate or disrupt quorum sensing, such drugs would constitute a new class of antibiotics. A new broad-spectrum antibiotic might result, for instance, if a way can be devised to undermine the interspecies signaling system.

Some novel research is focused on designing molecules that are structurally similar to autoinducers. The idea is to make a molecule that binds to the autoinducer detector of a particular bacterial species, blocking its ability to sense the appropriate signal molecule. This would prevent pathogenic bacteria from recognizing when they are assembled in great numbers and would thus avert the process that is normally triggered. Another approach is to design drugs that specifically interfere with the enzymes involved in synthesizing autoinducers, thus preventing the bacteria from sending out their signal molecules.

In some cases, host organisms already seem capable of manipulating quorum-sensing systems to their own advantage. For example, Pseudomonas aeruginosa, a bacterium present in soils and wetland habitats, poses a threat of infection to people already debilitated by cystic fibrosis, burns, cancer, or other conditions. By detecting and responding to autoinducer signals, the victim's body may be able to hinder the secretion of this bacterium's toxins. In other cases, hosts appear to produce molecules that mimic, and in some way interfere with, the quorum-sensing signals. This has been observed in some plants and algae.

While much applied research is directed toward finding ways to disrupt quorum sensing, the process can also be exploited in a positive way. For example, cell-to-cell communication may enhance the production of antibiotics. By finding ways to promote quorum sensing, scientists may discover how to improve the commercial production of natural antibiotics, enzymes, and other biochemicals useful in the prevention and treatment of disease, for the protection of food sources, and in industrial processes.

Whatever the practical applications, the investigation of quorum sensing promises to provide biologists with insights into a key step in the evolution of multicellular organisms. An appreciation of the molecular mechanisms that govern this bacterial process will lay the foundation for a better understanding of the development of organs and of cell-to-cell interactions and information processing in higher organisms.

To see the TED video of Bassler on Bacteria click here.

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