the evolution of quorum sensing in bacterial biofilms在生物膜细菌群体感应的进化.pdf

PLoS BIOLOGY The Evolution of Quorum Sensing in Bacterial Biofilms 1*[ 2[ 1 2* Carey D. Nadell , Joao B. Xavier , Simon A. Levin , Kevin R. Foster 1 Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America, 2 Center for Systems Biology, Harvard University, Bauer Laboratory, Cambridge, Massachusetts, United States of America Bacteria have fascinating and diverse social lives. They display coordinated group behaviors regulated by quorum- sensing systems that detect the density of other bacteria around them. A key example of such group behavior is biofilm formation, in which communities of cells attach to a surface and envelope themselves in secreted polymers. Curiously, after reaching high cell density, some bacterial species activate polymer secretion, whereas others terminate polymer secretion. Here, we investigate this striking variation in the first evolutionary model of quorum sensing in biofilms. We use detailed individual-based simulations to investigate evolutionary competitions between strains that differ in their polymer production and quorum-sensing phenotypes. The benefit of activating polymer secretion at high cell density is relatively straightforward: secretion starts upon biofilm formation, allowing strains to push their lineages into nutrient-rich areas and suffocate neighboring cells. But why use quorum sensing to terminate polymer secretion at high cell density? We find that deactivating polymer production in biofilms can yield an advantage by redirecting resources into growth, but that this advantage occurs only in a limited time window. We predict, therefore,