Deadly competition between sibling bacterial colonies
- Avraham Be'era,1,
- H. P. Zhanga,
- E.-L. Florina,
- Shelley M. Payneb,
- Eshel Ben-Jacobc,1 and
- Harry L. Swinneya,1
- aCenter for Nonlinear Dynamics and Department of Physics and
- bSection for Molecular Genetics and Microbiology, University of Texas, Austin, TX 78712; and
- cSchool of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel
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Contributed by Harry L. Swinney, November 26, 2008 (sent for review September 22, 2008)
Abstract
Bacteria can secrete a wide array of antibacterial compounds when competing with other bacteria for the same resources. Some of these compounds, such as bacteriocins, can affect bacteria of similar or closely related strains. In some cases, these secretions have been found to kill sibling cells that belong to the same colony. Here, we present experimental observations of competition between 2 sibling colonies of Paenibacillus dendritiformis grown on a low-nutrient agar gel. We find that neighboring colonies (growing from droplet inoculation) mutually inhibit growth through secretions that become lethal if the level exceeds a well-defined threshold. In contrast, within a single colony developing from a droplet inoculation, no growth inhibition is observed. However, growth inhibition and cell death are observed if material extracted from the agar between 2 growing colonies is introduced outside a growing single colony. To interpret the observations, we devised a simple mathematical model for the secretion of an antibacterial compound. Simulations of this model illustrate how secretions from neighboring colonies can be deadly, whereas secretions from a single colony growing from a droplet are not.
Footnotes
- 1To whom correspondence may be addressed. E-mail: swinney{at}chaos.utexas.edu, abeer{at}chaos.utexas.edu, or eshelbj{at}gmail.com
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Author contributions: A.B., H.P.Z., E.-L.F., S.M.P., E.B.-J., and H.L.S. designed research; A.B. performed the experiments; H.P.Z. did the mathematical modeling; A.B., H.P.Z., E.-L.F., S.M.P., E.B.-J., and H.L.S. analyzed data; and A.B., H.P.Z., E.-L.F., S.M.P., E.B.-J., and H.L.S. wrote the paper.
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The authors declare no conflict of interest.
- © 2009 by The National Academy of Sciences of the USA
