Although they have no sensory organs, by secreting and taking in chemicals from their surrounding environment, bacteria are able to communicate with each other and gain insight into what is going on around them. Even though there are millions of different kinds of bacteria with their own ways of sensing the world around them, Duke University bioengineers believe they have found a principle common to all of them.

It has been known for years that a process called "quorum sensing" underlies communication between bacteria. "Quorum sensing is a cell-to-cell communication mechanism that enables bacteria to sense and respond to changes in the density of the bacteria in a given environment," said Anand Pai, graduate student in bioengineering at Duke's Pratt School of Engineering. "It regulates a wide variety of biological functions such as bioluminescence, virulence, nutrient foraging and cellular suicide."

What the researchers recently discovered is that the total volume of bacteria in relation to the volume of their environment is key to quorum sensing - regardless of what kind of microbe is involved.

They define the process as "sensing potential", and it is described in detail in the July 2009 issue of the journal Molecular Systems Biology.

"Sensing potential is essentially the linking of an action to the number of cells and the size of their environment," said Lingchong You, assistant professor of biomedical engineering and a member of Duke's Institute for Genome Sciences & Policy and Center for Systems Biology. "For example, a small number of cells would act differently than the same number of cells in a much larger space. No matter what type of cell or their own quorum sensing abilities, the relationship between the size of a cell and the size of its environment is the common thread we see in all quorum sensing systems."

"This analysis provides novel insights into the fundamental design of quorum sensing systems," You said. "Also, the overall framework we defined can serve as a foundation for studying the dynamics and the evolution of quorum sensing, as well as for engineering synthetic gene circuits based on cell-to-cell communications."

The researchers said that a more complete understanding of communication between cells and bacteria is essential to the advancement of the new field of synthetic biology, where populations of genetically altered bacteria are "programmed" to do certain things. Such re-programmed bacterial gene circuits could see a wide variety of applications in medicine, environmental cleanup and biocomputing.

Source: http://news.duke.edu/2009/07/germcomm.html